Delphi

The theater at Delphi dates from about the 4th century B.C., although it was modified in later centuries; it seats about 5,000.

The theater gave spectators a stunning view of the entire valley below, including the circular temple of Athena Pronaia, which you can see in about the center of this photo:

The remains of storefronts leased to merchants catering to worshipers at Delphi: