People attend the Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace in Vienna, Austria, June 18, 2021. REUTERS/Lisi Niesner 

People attend the Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace in Vienna, Austria, June 18, 2021. REUTERS/Lisi Niesner 

People attend the Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace in Vienna, Austria, June 18, 2021. REUTERS/Lisi Niesner 

People attend the Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace in Vienna, Austria, June 18, 2021. REUTERS/Lisi Niesner 

People attend the Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace in Vienna, Austria, June 18, 2021. REUTERS/Lisi Niesner 

People attend the Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace in Vienna, Austria, June 18, 2021. REUTERS/Lisi Niesner 

Austria's Chancellor Sebastian Kurz, Kosovo's Prime Minister Albin Kurti, Montenegro's Prime Minister Zdravko Krivokapic and North Macedonia's Prime Minister Zoran Zaev attend the Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace after the Western Balkans conference in Vienna, Austria June 18, 2021. REUTERS/Lisi Niesner 

Austria's Chancellor Sebastian Kurz, Kosovo's Prime Minister Albin Kurti, Montenegro's Prime Minister Zdravko Krivokapic and North Macedonia's Prime Minister Zoran Zaev attend the Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace after the Western Balkans conference in Vienna, Austria June 18, 2021. REUTERS/Lisi Niesner 

Austria's Chancellor Sebastian Kurz and Kosovo's Prime Minister Albin Kurti attend the Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace after the Western Balkans conference in Vienna, Austria June 18, 2021. REUTERS/Lisi Niesner 

Austria's Chancellor Sebastian Kurz, Montenegro's Prime Minister Zdravko Krivokapic and North Macedonia's Prime Minister Zoran Zaev attend the Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace after the Western Balkans conference in Vienna, Austria June 18, 2021. REUTERS/Lisi Niesner 

Russian conductor Valery Gergiev and German opera singer Jonas Kaufmann are seen with the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

A woman wearing a protective face mask attends a performance by the Vienna Philharmonic Orchestra during the Summer Night Concert at the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People attend a performance by the Vienna Philharmonic Orchestra during the Summer Night Concert at the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People attend a performance by the Vienna Philharmonic Orchestra during the Summer Night Concert at the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

German opera singer Jonas Kaufmann gives an elbow bump with a musician of the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People attend a performance by the Vienna Philharmonic Orchestra during the Summer Night Concert at the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

German opera singer Jonas Kaufmann is seen with the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

German opera singer Jonas Kaufmann is seen with the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

Russian conductor Valery Gergiev is seen with the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

German opera singer Jonas Kaufmann is seen with the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

Russian conductor Valery Gergiev and German opera singer Jonas Kaufmann are seen with the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

Russian conductor Valery Gergiev is seen with the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

Russian conductor Valery Gergiev is seen with the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

The Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

The Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People wearing protective face masks attend a performance by the Vienna Philharmonic Orchestra during the Summer Night Concert at the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

A woman wearing a protective face mask and a plastic face shield attends a performance by the Vienna Philharmonic Orchestra during the Summer Night Concert at the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

German opera singer Jonas Kaufmann is seen with the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

Russian conductor Valery Gergiev is seen with the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

The Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

Russian conductor Valery Gergiev is seen with the Vienna Philharmonic Orchestra on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

German opera singer Jonas Kaufmann sings as the Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

German opera singer Jonas Kaufmann sings as the Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People attend a performance by the Vienna Philharmonic Orchestra during the Summer Night Concert at the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People attend a performance by the Vienna Philharmonic Orchestra during the Summer Night Concert at the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People attend a performance by the Vienna Philharmonic Orchestra during the Summer Night Concert at the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People attend a performance by the Vienna Philharmonic Orchestra during the Summer Night Concert at the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People attend a performance by the Vienna Philharmonic Orchestra during the Summer Night Concert at the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People arrive to attend the Vienna Philharmonic Orchestra performance on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People arrive to attend the Vienna Philharmonic Orchestra performance on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People wearing face masks take selfies before the Vienna Philharmonic Orchestra performance on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

People wearing face masks sit before the Vienna Philharmonic Orchestra performance on stage during the Summer Night Concert in the setting of Schoenbrunn Palace amid the coronavirus disease (COVID-19) outbreak in Vienna, Austria September 18, 2020. REUTERS/Lisi Niesner 

The Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace in Vienna, Austria, June 20, 2019. REUTERS/Lisi Niesner 

The Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace in Vienna, Austria, June 20, 2019. REUTERS/Lisi Niesner 

The Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace in Vienna, Austria, June 20, 2019. REUTERS/Lisi Niesner 

The Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace in Vienna, Austria, June 20, 2019. REUTERS/Lisi Niesner 

Spectators gather in the gardens of Schoenbrunn Palace as the Vienna Philharmonic Orchestra performs the Summer Night Concert in Vienna, Austria, June 20, 2019. REUTERS/Lisi Niesner 

The Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace in Vienna, Austria, June 20, 2019. REUTERS/Lisi Niesner 

The Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace in Vienna, Austria, June 20, 2019. REUTERS/Lisi Niesner 

Spectators gather in the gardens of Schoenbrunn Palace as the Vienna Philharmonic Orchestra performs the Summer Night Concert in Vienna, Austria, June 20, 2019. REUTERS/Lisi Niesner 

Spectators gather as the Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert in the setting of Schoenbrunn Palace in Vienna, Austria June 20, 2019. REUTERS/Lisi Niesner 

Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace in Vienna, Austria June 20, 2019. REUTERS/Lisi Niesner 

Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace in Vienna, Austria June 20, 2019. REUTERS/Lisi Niesner 

Summer Night Concert of the Vienna Philharmonic Orchestra in the setting of Schoenbrunn Palace in Vienna, Austria June 20, 2019. REUTERS/Lisi Niesner 

Spectators gather as the Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert at the baroque gardens of Schoenbrunn Palace in Vienna, Austria, May 31, 2018. REUTERS/Lisi Niesner TPX IMAGES OF THE DAY 

Russian-Austrian soprano singer Anna Netrebko and the Vienna Philharmonic Orchestra perform on stage during the Summer Night Concert in front of Schoenbrunn Palace in Vienna, Austria, May 31, 2018. REUTERS/Lisi Niesner 

Spectators gather as the Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert at the baroque gardens of Schoenbrunn Palace in Vienna, Austria, May 31, 2018. REUTERS/Lisi Niesner 

Spectators gather as the Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert at the baroque gardens of Schoenbrunn Palace in Vienna, Austria, May 31, 2018. REUTERS/Lisi Niesner 

Spectators gather as the Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert at the baroque gardens of Schoenbrunn Palace in Vienna, Austria, May 31, 2018. REUTERS/Lisi Niesner 

Spectators gather as the Vienna Philharmonic Orchestra performs on stage during the Summer Night Concert at the baroque gardens of Schoenbrunn Palace in Vienna, Austria, May 31, 2018. REUTERS/Lisi Niesner