Panathenaic Stadium.

The marble stadium that hosted the first modern Olympics in 1896 and  lies on top of an ancient stadium built in 330 B.C.
In ancient times, the stadium on this site was used to host the athletic portion of the Panathenaic Games, in honor of the Goddess Athena. During classical times, it had wooden seating. In 329 BCE it was rebuilt in marble by the archon Lycurgus and in 140 CE was enlarged and renovated by Herodes Atticus, giving a seated capacity of 50,000.