The Senate subway at the U.S. Capitol, normally a busy spot for lawmakers to be interviewed by reporters, is empty during the coronavirus disease (COVID-19) outbreak in Washington, U.S., April 15, 2020. REUTERS/Jonathan Ernst 

Civil defense members look for survivors after rain storms unleashed flash floods, near the Dead Sea, Jordan October 26, 2018. REUTERS/Muhammad Hamed TPX IMAGES OF THE DAY 

A miner uses a drill inside 'El Teniente' copper mine of Chile's state copper giant Codelco in Rancagua, Chile March 21, 2018. REUTERS/Ivan Alvarado 

A pair of shoes hang on the wall of a troglodyte house on the outskirts of Matmata, Tunisia, February 4, 2018. REUTERS/Zohra Bensemra SEARCH "BENSEMRA MATMATA" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. 

A general view of troglodyte houses in Matmata, Tunisia, February 6, 2018. REUTERS/Zohra Bensemra SEARCH "BENSEMRA MATMATA" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. TPX IMAGES OF THE DAY. TPX IMAGES OF THE DAY 

A general view shows the interiors of what the Israeli military say is a cross-border attack tunnel dug from Gaza to Israel, on the Israeli side of the Gaza Strip border near Kissufim January 18, 2018. REUTERS/Jack Guez/Pool 

A man holds on to a handrail strap as he rides the subway in Buenos Aires, Argentina, June 13, 2017. REUTERS/Marcos Brindicci 

Commuters walk during the evening rush after arriving at a subway station in Budapest, Hungary, June 13, 2017. REUTERS/Laszlo Balogh 

A commuter waits for a train at a subway station in Budapest, Hungary, June 13, 2017. REUTERS/Laszlo Balogh 

A bird walks inside a commuter underground tube train at Stratford station, east London, Britain, June 13, 2017. REUTERS/Russell Boyce 

A view of the cubicle "Dei fornai" inside Rome's oldest underground burial networks, Domitilla Catacombs, Italy, May 30, 2017. REUTERS/Remo Casilli TPX IMAGES OF THE DAY 

Vehicles ply inside the Chenani-Nashri Tunnel, Asia's longest bi-directional tunnel, on the Jammu-Srinagar National Highway at Chenani, northeast of Jammu April 3, 2017. REUTERS/Mukesh Gupta 

A man hurries past free newspapers stacked for commuters to take at Canary Wharf underground tube station in London, Britain, March 14, 2017. REUTERS/Russell Boyce 

Rebel fighters inspect a tunnel they said belonged to Islamic State fighters which connects the city to Aqeel mountain, in the northern Syrian city of al-Bab, Syria March 13, 2017. REUTERS/Khalil Ashawi 

An entrance to an underground Johannesburg's oldest gold mine is seen in Langlaagte, South Africa September 12, 2016. REUTERS/Siphiwe Sibeko 

A homeless man naps in an underground passage in Seoul, South Korea, July 14, 2016. REUTERS/Kim Hong-Ji 

An entrance to a tunnel which Israel's military said it had discovered is seen just outside the southern Gaza Strip May 6, 2016. REUTERS/ Amir Cohen TPX IMAGES OF THE DAY

Manuel Barrantes digs underground, as he continues to expand his house in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

Lidieth Barrantes reads a book in one of the rooms of the house that her father built underground in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

Cristal Barrantes makes a bed in her bedroom at the house that her husband Manuel Barrantes built underground in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

Lidieth Barrantes and her daughter walk in a hallway of a house built underground by Manuel Barrantes in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate TPX IMAGES OF THE DAY

A collection of old things and a bedroom are pictured in the house built by Manuel Barrantes underground in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

Manuel Barrantes leaves his home that built underground in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

A hallway of a house built underground by Manuel Barrantes is pictured in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

A figure of a skeleton is seen painted in a hallway of the house built underground by Manuel Barrantes in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

Manuel Barrantes shaves in a bathroom of his house he built underground in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

Family members of Manuel Barrantes sit together in one of the rooms of the house he built underground in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

Characters from the cartoon "The Flintstones" are seen painted in a hallway of the house built underground by Manuel Barrantes in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

Manuel Barrantes shows part of a collection of old things in one of the rooms of the house he built underground in San Isidro de Perez Zeledon, Costa Rica March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

Manuel Barrantes enters his house he built underground in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). Picture taken March 14, 2016. REUTERS/Juan Carlos Ulate 

People stand on the bottom of a staircase that leads to an underground centre for children during its opening ceremony in Aleppo, Syria, January 21, 2016. The sign reads in Arabic: "My Childhood club, a friend of the child; Masarat, the Syrian Organisation for Humanitarian Care and Development. " REUTERS/Abdelrahmin Ismail 

Internally displaced people fills buckets with water sourced from an underground well during the cold weather in Jerjnaz camp, in Idlib province, Syria, January 5, 2016. REUTERS/Khalil Ashawi 

Internally displaced Syrians stand inside their makeshift shelter that is an underground cave in Om al-Seer, southern Idlib countryside, Syria December 26, 2015. REUTERS/Khalil Ashawi TPX IMAGES OF THE DAY

A man wearing a mask walks through an underground passage as smog covers China's capital Beijing on an extremely polluted day, December 1, 2015. REUTERS/Jason Lee 

People enter an underground crossing in central Pyongyang October 11, 2015. Picture taken October 11, 2015. To match Insight NORTHKOREA-CHANGE/ REUTERS/Damir Sagolj 

French firemen use a pump to removed water from an underground parking garage at a residential apartment building the day after torrential rains caused flooding in Mandelieu-La Napoule, France, October 5, 2015. Two people were still missing on Monday after flash floods on the French Riviera killed at least 19 people over the weekend, prompting the government to declare a natural disaster in the southeastern tourist region. Some 5,000 homes were still without electricity on Monday morning after as many as 70,000 suffered blackouts the previous evening. REUTERS/Jean-Paul Pelissier

French firemen use a pump to removed water from an underground parking garage at a residential apartment building the day after torrential rains caused flooding in Mandelieu-La Napoule, France, October 5, 2015. Four people were still missing on Monday after flash floods on the French Riviera killed at least 17 people over the weekend, prompting the government to declare a natural disaster in the southeastern tourist region. Some 5,000 homes were still without electricity on Monday morning after as many as 70,000 suffered blackouts the previous evening. REUTERS/Jean-Paul Pelissier

People walk through The World Trade Center's underground passageway in lower Manhattan in New York August 26, 2015. REUTERS/Brendan McDermid 

A woman walks through The World Trade Center's underground passageway in lower Manhattan in New York August 26, 2015. REUTERS/Brendan McDermid 

People walk through The World Trade Center's underground passageway in lower Manhattan in New York August 26, 2015. REUTERS/Brendan McDermid 

People walk through The World Trade Center's underground passageway in lower Manhattan in New York August 26, 2015. REUTERS/Brendan McDermid 

A street vendor waits for customers at an underground passage in Istanbul, Turkey, August 18, 2015. REUTERS/Murad Sezer 

People queue to buy staple items in the underground parking lot of a state-run Bicentenario supermarket in Caracas August 4, 2015. Venezuelan supermarkets are increasingly being targeted by looters, as swollen lines and prolonged food shortages spark frustration in the OPEC nation struggling with an economic crisis. Shoppers routinely spend hours in lines to buy consumer staples ranging from corn flour to laundry soap, turning lines into venues for shoving matches and now more frequent attempts to plunder shops. Picture taken on August 4, 2015. REUTERS/Carlos Garcia Rawlins 

Reuters photographer Issei Kato casts a shadow on the entrance of an underground shopping complex in Hiroshima, western Japan July 28, 2015. On August 6, 1945, the U.S. dropped the atomic bomb on Hiroshima, killing about 140,000 by the end of the year in a city of 350,000 residents, in the world's first nuclear attack. Three days later, a second atomic bomb was dropped on Nagasaki. Influenced by the shadows scorched into outdoor surfaces by the heat of the blasts 70 years ago, Reuters photographer Issei Kato pays homage to survivors, residents and historic buildings in both cities in a personal project that captures the shadows of today. REUTERS/Issei Kato PICTURE 11 OF 12 FOR WIDER IMAGE STORY "SHADOWS OF HIROSHIMA AND NAGASAKI".
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People tour the Luray Caverns in Luray, Virginia, July 30, 2015. The caverns, some as deep as 164 feet below the earth, featuring stalactites, stalagmites, are a top tourist attraction and see thousands of visitors each year. Photo taken July 30, 2015 REUTERS/Carlo Allegri 

A street vendor waits for customers near an underground passage in central Kiev, Ukraine, July 29, 2015. REUTERS/Gleb Garanich 

An oxygen tank stands near a rail cart inside a tunnel connected to the Altiplano Federal Penitentiary and used by drug lord Joaquin 'El Chapo' Guzman to escape, in Almoloya de Juarez, on the outskirts of Mexico City, July 15, 2015. U.S. law enforcement officials met with agents of the Mexican attorney general's office this week to share information related to the escape from prison of Guzman and coordinate efforts to apprehend him, a Mexican government official said on Wednesday. REUTERS/Edgard Garrido 

A flashlight illuminates a judicial worker as he shines a torch into an area of the tunnel connected to the Altiplano Federal Penitentiary and used by drug lord Joaquin 'El Chapo' Guzman to escape, in Almoloya de Juarez, on the outskirts of Mexico City, July 14 , 2015. Mexican authorities must have colluded with Joaquin "El Chapo" Guzman to enable the country's top drug lord to escape from a maximum security prison at the weekend, Interior Minister Miguel Angel Osorio Chong said on Monday.Guzman sparked a massive manhunt after escaping from Altiplano prison on Saturday night in a mile-long underground tunnel that led from his cell into a deserted building, dealing a bitter blow for President Enrique Pena Nieto. REUTERS/Edgard Garrido 

Ein Karem resident, Tal, stands in a ritual bath that was discovered under his family's house in Jerusalem, July 1, 2015. The Jerusalem family has found a 2,000-year-old Jewish ritual bath under their house while renovating the living room floor, Israel's Antiquities Authority said on Wednesday. Pottery vessels inside the rock-hewn bath helped archaeologists date the discovery to the 1st century. The house is in the village of Ein Karem, the traditional birthplace of John the Baptist . REUTERS/Ronen Zvulun

A Toyota i-Road electric vehicle drives in a underground parking lot in Tokyo April 9, 2015. Tokyoites will get a chance to zip around town on Toyota Motor Corp's three-wheeled electric car-cum-motorbike from Friday, in a trial aimed at crafting a global business model to reduce gridlock and pollution. REUTERS/Thomas Peter

A girl reads a book while resting in the facilities of Belarus' Republican Clinic of Speleotherapy within a salt mine near the town of Soligorsk, south of Minsk, February 19, 2015. According to the state clinic, more than 7,000 children and adults seek medical treatment for respiratory illness each year in the subsurface chambers of its facilities, located 420 metres underground between layers of potassium and stone salts in an operational salt mine. REUTERS/Vasily Fedosenko (BELARUS - Tags: HEALTH SOCIETY) 

Mariam, a 9-year-old girl, carries her brother as she stands with other children at an underground ancient cemetery in Jabal al-Zawiya in the southern countryside of Idlib November 26, 2014. Residents are using ancient caves and cemeteries as underground shelters to hide in during shelling from forces loyal to President Bashar al-Assad. Picture taken November 26, 2014. REUTERS/Khalil Ashawi (SYRIA - Tags: POLITICS CIVIL UNREST CONFLICT TPX IMAGES OF THE DAY) 

A member of the Armed Forces of Bosnia and Herzegovina stands near Josip Broz Tito's portraits in Tito's underground secret bunker (ARK) in Konjic, October 16, 2014. In the early 1950s, Tito, the late leader of the former Yugoslavia, ordered the building of the secret bunker, located 900 feet (270 m) underground and near the Bosnian town of Konjic, to safeguard the country's ruling class in case of a nuclear attack. Construction at the complex, which had a cost equivalent price tag of $4.6 billion, continued until 1979, the year before Tito died. Picture taken October 16, 2014. REUTERS/Dado Ruvic (BOSNIA AND HERZEGOVINA - Tags: POLITICS MILITARY SOCIETY) 

Coal miner Mike Hawks, 53, stands in an underground tunnel at a coal processing facility near Gilbert, West Virginia May 22, 2014. With coal production slowing due to stricter environmental controls, the availability of natural gas and a shift to surface mining, the state's coal country has been hit hard with job losses and business closures. Picture taken May 22, 2014. REUTERS/Robert Galbraith (UNITED STATES - Tags: BUSINESS COMMODITIES ENERGY EMPLOYMENT SOCIETY TPX IMAGES OF THE DAY)

ATTENTION EDITORS - PICTURE 08 OF 27 FOR WIDER IMAGE STORY 'DECLINE ALONG 'THE KING COAL HIGHWAY''

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A woman walks through an underground passage on a hazy night in central Beijing October 8, 2014. REUTERS/Jason Lee (CHINA - Tags: ENVIRONMENT TPX IMAGES OF THE DAY) 

An empty waiting bench is seen as one of the last German railway Deutsche Bahn regional trains of the day leaves Frankfurt's main railway station October 7, 2014. German travellers face more disruption after train drivers' union GDL called for a nine-hour nationwide strike starting Tuesday evening in a row over pay and conditions with state-owned rail operator Deutsche Bahn. REUTERS/ Kai Pfaffenbach (GERMANY - Tags: BUSINESS EMPLOYMENT CIVIL UNREST TRANSPORT TPX IMAGES OF THE DAY) 

Forces loyal to Syria's President Bashar al-Assad inspect an underground base where caves were dug by rebel fighters in al-Hareeqa village, after the forces said they have regained control of the area in Hama countryside October 5, 2014. REUTERS/George Ourfalian (SYRIA - Tags: POLITICS CIVIL UNREST CONFLICT) 

A woman sits in a basement used as a shelter from artillery fire in Donetsk, September 3, 2014. New shelling of the rebel stronghold of Donetsk, sending plumes of grey smoke from near the city's airport, undermined confidence in an end to hostilities. REUTERS/Maxim Shemetov (UKRAINE - Tags: POLITICS CIVIL UNREST CONFLICT TPX IMAGES OF THE DAY) 

Members of Ukrainian police special task force "Kiev-1" inspect weapons hidden by pro-Russian separatists in the basement of an unfinished house in Slaviansk September 2, 2014. Russian troops are strengthening their positions in eastern Ukraine and using aid shipments to smuggle in arms and other supplies to separatist forces, Kiev's military said on Tuesday. REUTERS/Stanislav Belousov (UKRAINE - Tags: POLITICS CIVIL UNREST MILITARY CONFLICT TPX IMAGES OF THE DAY)