The ancient site of the city is centered on the rocky hill of the Acropolis. In ancient times the port of Piraeus (modern name Pireas) was a separate city, but it has now been absorbed into greater Athens. The rapid expansion of the city initiated in the 50's and 60's continues today, especially towards the East and North East (a tendency that is greatly related to the new Eleftherios Venizelos International Airport and Attiki Odos, the freeway that cuts across Attica). By this process, Athens has engulfed many former suburbs and villages in Attica and continues to do so.