Decelea, Dekéleia), was a deme and ancient village in northern Attica serving as a trade route connecting Euboea with Athens, Greece. It was situated near the entrance of the eastern pass across Mount Parnes, which leads from the northeastern part of the Athenian plain to Oropus, and from thence both to Tanagra on the one hand, and to Delium and Chalcis on the other. It was situated about 120 stadia from Athens, and the same distance from the frontiers of Boeotia. It was visible from Athens and from its heights the ships entering the harbour of Piraeus were visible as well.