Olba, later Diocaesarea, is an ancient Seleucid city in Rough Cilicia in Turkey’s rugged Eastern Mediterranean coastline. In the Hellenistic period, the city was the centre of worship of Zeus Olbios whose sanctuary was located about 4 km to the west. Erected during the reign of the Seleucids, the temple, Corinthian in style, is the oldest peripteral temple (6×12 columns) in Asia Minor. Other monuments from the Hellenistic period include a 22m-high tower and a mausoleum. The Roman city of Diocaesarea later developed in the 1st century AD around the temple devoted to Zeus Olbios and its ruins today lie partly within the grounds of the village of Uzuncaburç (Turkish for high tower and referring to the Hellenistic tower) and its immediate surroundings.
The most important Roman buildings on the site date from the 1st to the 3rd century AD and include a theatre, a nymphaeum, an aqueduct, and many tombs dug in the rock. The city is entered through a monumental gate, of which five columns have survived. Then a colonnaded street runs alongside the temple of Zeus Olbios and leads to the temple of Tyche. To the north-west, a three-arched Roman gate leads out of town.