The Acropolis set at the top of the tableland (about 156m above sea level and 92m over the modern city) with vertical drops on every side is considered the cradle of classic Greece. Over a surface of less than three hectares the ancient “Sacred City” was built with the sanctuaries and the temples that protected the city’s treasures. Greek artists built here, during different epochs, a complex of monuments with no equals anywhere in the world. It is a very popular site with tourists that come all year round to see the ruins of such classic treasures. The visiting hours are from 8.00 to 17.00 from October to March and from 8.00 to 19.00 from April to October, however due to the excessive heat during summer it is advisable to visit the Acropolis during the early hours of the morning or late afternoon. To name but a few of the important monuments, the Parthenon in the centre of the Acropolis is no doubt the most famous work of art of Greek architecture, followed by the Temple of Athena Nike, Erettaeus, the Theatre of Dionisus on the south side of the ancient city and the Agrippa monument. Northwest of the Acropolis, the Agora was the heart of the administration and public affairs of Athens as well as the marketplace (the agora is open to visitors from 8.00 to 15.00 Tuesday to Sunday, closed on Mondays).