A woman visits the archeological site of Acropolis in Athens, Greece, on March 22, 2021. On Monday, open-air archeological sites, including the Acropolis hill in Athens, reopened for the first time since the start of the lockdown. Only a small group of visitors is allowed to visit and the use of protective face masks is obligatory. [Photo/Xinhua]

A couple wearing face masks take a selfie at the archeological site of Acropolis in Athens, Greece, on March 22, 2021. On Monday, open-air archeological sites, including the Acropolis hill in Athens, reopened for the first time since the start of the lockdown. Only a small group of visitors is allowed to visit and the use of protective face masks is obligatory. [Photo/Xinhua]

People visit the archeological site of Acropolis in Athens, Greece, on March 22, 2021. On Monday, open-air archeological sites, including the Acropolis hill in Athens, reopened for the first time since the start of the lockdown. Only a small group of visitors is allowed to visit and the use of protective face masks is obligatory. [Photo/Xinhua]

People visit the Ancient Theater of Dionysus next to the Acropolis in Athens, Greece, on March 22, 2021. On Monday, open-air archeological sites, including the Acropolis hill in Athens, reopened for the first time since the start of the lockdown. Only a small group of visitors is allowed to visit and the use of protective face masks is obligatory. [Photo/Xinhua]

People visit the archeological site of Acropolis in Athens, Greece, on March 22, 2021. On Monday, open-air archeological sites, including the Acropolis hill in Athens, reopened for the first time since the start of the lockdown. Only a small group of visitors is allowed to visit and the use of protective face masks is obligatory. [Photo/Xinhua]

A man visits the archeological site of Acropolis in Athens, Greece, on March 22, 2021. On Monday, open-air archeological sites, including the Acropolis hill in Athens, reopened for the first time since the start of the lockdown. Only a small group of visitors is allowed to visit and the use of protective face masks is obligatory. [Photo/Xinhua]

People visit the archeological site of Acropolis in Athens, Greece, on March 22, 2021. On Monday, open-air archeological sites, including the Acropolis hill in Athens, reopened for the first time since the start of the lockdown. Only a small group of visitors is allowed to visit and the use of protective face masks is obligatory. [Photo/Xinhua]