For sure there is many places around Attica of great importance. Historical , mythical or religious, Attica have a lot of things to discover , explore and visit.
One of the most holy place is Eleusis. A city between Athens and Corinth. Famous for its rites from the Classical Antiquity. Every year in the month Boedromion (The month September/October in ancient Hellenic calendar), Athenians were taking the "Sacred Way" from Athens to Eleusis.