Didim is a small town, popular seaside holiday resort, and district of Aydın Province on the Aegean coast of western Turkey, 123 km (76 mi) from the provincial capital city of Aydın. Didim is the site of the antique city of Didyma with its ruined Temple of Apollo.
Didim takes its name from ancient Didyma, situated close to the modern town. During the Ottoman Empire era, the town was known as Yoranda or Yoran, and under the modern Republic of Turkey, it was originally named Hisar (“Castle”). Following its destruction in an earthquake in 1955, the town was rebuilt and renamed Yenihisar (“New Castle”). The town was part of Söke district until 1991. The area became a top-level district of Aydın Province and was given the ancient name Didim in 1997 to distinguish it from the many other places in Turkey named Yenihisar.