Different Attalid kings added to it and made a huge group of buildings. The buildings stretch out from the Acropolis in many directions, using the natural way of that part of the earth. The agora, on the south on the lowest level, has galleries along its sides, with "stoai" (beautiful tall stone things to hold up the roof.) The agora is the beginning of a street which goes through the whole Acropolis. On the east and top of the rock are the buildings of the organizers, leaders and soldiers. On the west side, at a middle level, are religious buildings. One of the biggest ones is the one with the Pergamon Altar which is called "of the gods and of the giants" and is one of the most beautiful pieces of Greek sculpture. A very big theatre has benches stretched out over the sides of the hill, for people to sit on, and is able to hold almost 10,000 people.