Carmarthen, kur MAHR thuhn or kahr MAHR thuhn, is a town in southwest Wales. In Welsh, the town's name is Caerfyrddin. Carmarthen is a major commercial center and market town and also a center for tourism in the area. The town is near the mouth of the River Tywi, about 7 1/2 miles (12 kilometers) inland from Carmarthen Bay on the Bristol Channel, an arm of the Atlantic Ocean. Carmarthen is the main administrative center for the unitary authority of Carmarthenshire, a governmental unit responsible for providing local government services within its boundaries. The town is built on the banks of the River Tywi, and has several historic buildings, including the Guildhall, completed in 1777, and the remains of Carmarthen Castle, built in the early 1100's.