Didim takes its name from the old Didyma, located near the modern city. During the Ottoman Empire era, the city was known as Yoranda or Yoran, and under the modern Republic of Turkey, it was originally called Hisar (“Castle”). After its destruction in a 1955 earthquake, the city was rebuilt and changed its name to Yenihisar (“New Castle”). The city was part of the Sรถke district until 1991. The area became an important district of Aydin Province, and in 1997 it was given its old name Didim to distinguish it from many other places in Turkey called Yenihisar.