Visitors attend a concert at the Athens Acropolis Museum in Greece, on March 31, 2018. The summer season of the Athens Acropolis Museum was launched Friday evening with a music concert featuring an ancient Greek organ known as the "hydraulis." At the concert held in the museum's Parthenon Gallery, visitors had the opportunity to enjoy a performance featuring the musical instrument played by the Greek organist Ourania Gassiou, as well as a harp performance. (Xinhua/Lefteris Partsalis)?