The entrance gate to a classical temenos, temple, or other sacred enclosure; the gateway that stands in front of a pylon. At the Acropolis in Athens, the monumental Propylaia (Propylaeum) was built in 437 BC on the same orientation as the Parthenon. This monumental entrance had various forms generally involving a colonnade (of four columns) positioned in front of an entrance cut into a continuous enclosure wall. The propylaeum may have columns both outside and inside the enclosure wall.