Didyma (Turkey) — A Well Preserved Temple
The Apollo Temple at Didyma was the site of a world famous oracle of Apollo (compare Delphi! in Greece). About 300 B.C. Seleucus I Nicator began building the well-preserved Hellenistic Temple that still stands today. For the next 500(!) years it was under construction. It went out of use during the fourth century A.D. as Christianity grew stronger in this region.