town, capital of Janūb Sīnāʾ muḥāfaẓah (governorate), southwestern Sinai Peninsula, Egypt. It lies on the coast of the Gulf of Suez. Aṭ-Ṭūr has been an administrative centre and seaport since the Roman and Byzantine periods. In the town the Byzantine emperor Justinian (527–565) built a monastery, its ruins still extant. From the medieval period into the early 20th century, the town served as a quarantine station for hajj pilgrims. Until the opening of the Suez Canal (1869), Aṭ-Ṭūr was also a port for the Red Sea trade.

Only limited agricultural activity is carried on in the vicinity by the Twara Bedouin, for whom Aṭ-Ṭūr is a traditional gathering place. Their crops include dates, vegetables, and barley. Stock raising is economically important; camels, donkeys, sheep, and goats are raised, but the Twara must migrate seasonally to find pasture for their flocks. Aṭ-Ṭūr has also developed a fishing industry. The main spur for the town's redevelopment has been the exploitation of petroleum deposits along the coast of the gulf since the 1970s. The town serves as a centre for nearby oil fields.

The town's population is partly Christian, and there is an active monastery, a large church, and a guesthouse operated by monks of the Greek Orthodox St. Catherine's monastic order. There is also a sulfur hot spring and spa in the hills northeast of the town. The coastal highway links Aṭ-Ṭūr to the Nile River valley by way of the Aḥmad Hamdi Tunnel (1980) under the Suez Canal. Pop. (1996) 12,072.