Shahr-e Rey or simply Ray is the capital of Ray County in Tehran Province, Iran. Formerly a distinct city, it has now been absorbed into the metropolitan area of Greater Tehran as the 20th district of municipal Tehran, the capital city of the country.
Historically known as Rhages, Rhagae and Arsacia, Ray is the oldest existing city in Tehran Province. In the classical era, it was a prominent city belonging to Media, the political and cultural base of the Medes. Ancient Persian inscriptions and the Avesta, among other sources, attest to the importance of ancient Ray. Ray is mentioned several times in the Apocrypha. It is also shown on the 4th-century Peutinger Map. The city was subject to severe destruction during the medieval invasions by the Arabs, Turks, and Mongols. Its position as a capital city was revived during the reigns of the Buyid Daylamites and the Seljuk Turks. Ray is richer than many other ancient cities in the number of its historical monuments.