Delphi is a famous ancient Greek sanctuary that was considered the center, or navel, of the world. It was home to the oracle of Pythia and an important religious site dedicated to the god Apollo. An omphalos stone monument marked the supposed center of the world at Delphi. The archaeological museum at Delphi houses artifacts from the sanctuary dating from the Mycenean period through the Byzantine era and gives visitors insight into the important religious site. The ancient theater at Delphi, built in the 4th century BC but remodeled over time, offers views of the entire sanctuary below.