A view shows human remains found in an archeological dig, during the search for Irish nobleman Hugh O'Donnell in Valladolid, Spain May 29, 2020. REUTERS/Juan Medina

A man wearing a face mask works in an archeological dig, during the search for Irish nobleman Hugh O'Donnell in Valladolid, Spain May 29, 2020. REUTERS/Juan Medina

A man wearing a face mask works in an archeological dig, during the search for Irish nobleman Hugh O'Donnell in Valladolid, Spain May 29, 2020. REUTERS/Juan Medina

A view shows human remains found in an archeological dig, during the search for Irish nobleman Hugh O'Donnell in Valladolid, Spain May 29, 2020. REUTERS/Juan Medina

A view shows human remains found in an archeological dig, during the search for Irish nobleman Hugh O'Donnell in Valladolid, Spain May 29, 2020. REUTERS/Juan Medina

A view shows human remains found in an archeological dig, during the search for Irish nobleman Hugh O'Donnell in Valladolid, Spain May 29, 2020. REUTERS/Juan Medina

A view shows human remains found in an archeological dig, during the search for Irish nobleman Hugh O'Donnell in Valladolid, Spain May 29, 2020. REUTERS/Juan Medina

A view shows human remains found in an archeological dig, during the search for Irish nobleman Hugh O'Donnell in Valladolid, Spain May 29, 2020. REUTERS/Juan Medina

An archaeologist looks at parts of a wooden Roman ship dated to the 3rd century AD, at the ancient city of Viminacium, near Kostolac, Serbia, May 28, 2020. Picture taken May 28, 2020. REUTERS/Marko Djurica

Archaeologists look at parts of a wooden Roman ship dated to the 3rd century AD, at the ancient city of Viminacium, near Kostolac, Serbia, May 28, 2020. Picture taken May 28, 2020. REUTERS/Marko Djurica

An archaeologist looks at parts of a wooden Roman ship dated to the 3rd century AD, at the ancient city of Viminacium, near Kostolac, Serbia, May 28, 2020. Picture taken May 28, 2020. REUTERS/Marko Djurica

Archaeologists look at 9 meters-long front section of a wooden Roman ship dated to the 3rd century AD, at the ancient city of Viminacium, near Kostolac, Serbia, May 28, 2020. Picture taken May 28, 2020. REUTERS/Marko Djurica

Archaeologists look at 9 metre-long front section of a wooden Roman ship dated to the 3rd century AD, at the ancient city of Viminacium, near Kostolac, Serbia, May 28, 2020. Picture taken May 28, 2020. REUTERS/Marko Djurica

Archaeologists look at 9 metre-long front section of a wooden Roman ship dated to the 3rd century AD, at the ancient city of Viminacium, near Kostolac, Serbia, May 28, 2020. Picture taken May 28, 2020. REUTERS/Marko Djurica

Archaeologist Miomir Korac looks at 9 metre-long front section of a wooden Roman ship dated to the 3rd century AD, at the ancient city of Viminacium, near Kostolac, Serbia, May 28, 2020. Picture taken May 28, 2020. REUTERS/Marko Djurica

Italian tourists visit the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

The archaeological site of the ancient Roman city of Pompeii is seen, as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Italian tourists visit the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Workers cut the grass at the archaeological site of the ancient Roman city of Pompeii, as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

A fresco is pictured at the archaeological site of the ancient Roman city of Pompeii, as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

The archaeological site of the ancient Roman city of Pompeii is seen, as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

The archaeological site of the ancient Roman city of Pompeii is seen, as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

An Italian tourist wearing a protective face mask visits the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Italian tourists wearing protective face masks visit the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Signs showing the imposed restrictions are pictured at the archaeological site of the ancient Roman city of Pompeii, which reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

An Italian tourist poses for a photo as she visits the archaeological site of the ancient Roman city of Pompeii, which reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Italian tourists wearing protective face masks visit the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Italian tourists wearing protective face masks visit the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Italian tourists visit the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

An Italian tourist wearing a protective face mask visits the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

An Italian tourist wearing a protective face mask sits down as she visits the archaeological site of the ancient Roman city of Pompeii, which reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

The archaeological site of the ancient Roman city of Pompeii is seen, as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Italian tourists wearing protective face masks visit the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Italian tourists wearing protective face masks visit the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Italian tourists wearing protective face masks visit the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Italian tourists wearing protective face masks arrive to visit the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

Italian tourists wearing protective face masks visit the archaeological site of the ancient Roman city of Pompeii as it reopens to the public with social distancing and hygiene rules, after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

An Italian tourist wearing a protective face mask gets her temperature measured at the entrance of the archaeological site of the ancient Roman city of Pompeii, as it reopens to the public with social distancing and hygiene rules after months of closure due to an outbreak of the coronavirus disease (COVID-19), in Pompeii, Italy, May 26, 2020. REUTERS/Ciro De Luca

A member of the Spanish Emergency Military Unit (UME) wearing a full personal protective equipment disinfects outside the Archaeological Museum amid the coronavirus disease (COVID-19) outbreak, in Madrid, Spain May 25, 2020. REUTERS/Sergio Perez

Members of the Spanish Emergency Military Unit (UME) wearing full personal protective equipments disinfect outside the Archaeological Museum amid the coronavirus disease (COVID-19) outbreak, in Madrid, Spain May 25, 2020. REUTERS/Sergio Perez

A member of the Spanish Emergency Military Unit (UME) wearing a full personal protective equipment disinfects outside the Archaeological Museum amid the coronavirus disease (COVID-19) outbreak, in Madrid, Spain May 25, 2020. REUTERS/Sergio Perez

Visitors prepare to enter the Acropolis archaeological site, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A Culture ministry employee wearing a face shield stands at the Acropolis' Propylaea as the archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

Culture ministry employees wear face shields at the entrance of the Acropolis archaeological site as it opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A Culture ministry employee cleans a plexiglass separator at the Acropolis' Propylaea as the archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A Culture ministry employee wearing a face shield stands in front of the Parthenon temple as the Acropolis archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A Culture ministry employee wearing a face mask stands in front of the Parthenon temple as the Acropolis archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A social distancing marker reads "Stay Here!" with the Parthenon temple seen in the background, as the Acropolis archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A Culture ministry employee cleans a metal bar at the Acropolis' Propylaea as the archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A Culture ministry employee wearing a face mask stands in front of the Parthenon temple as the Acropolis archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A visitor takes a photo of the Parthenon temple next to a social distancing marker, as the Acropolis archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A Culture ministry employee wearing a face shield stands at the Acropolis' Propylaea as the archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A Culture ministry employee wears a protective face mask as the Acropolis' archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

Visitors walk past the Parthenon temple as the Acropolis archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19, in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

Visitors wearing protective face masks walk past the Parthenon temple as the Acropolis archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

Visitors walk past the Parthenon temple as the Acropolis archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19, in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A Culture ministry employee wearing a face mask stands in front of the Parthenon temple as the Acropolis archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A Culture ministry employee wearing a face mask stands in front of the Parthenon temple as the Acropolis archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

Visitors prepare to enter the Acropolis archaeological site, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis

A Culture ministry employee wears a protective face mask as the Acropolis' archaeological site opens to visitors, following the easing of measures against the spread of the coronavirus disease (COVID-19), in Athens, Greece, May 18, 2020. REUTERS/Alkis Konstantinidis