The Isle of Portland is a limestone tied island, 6 kilometres (4 mi) long by 2.7 kilometres (1.7 mi) wide, in the English Channel. Portland is 8 kilometres (5 mi) south of the resort of Weymouth, forming the southernmost point of the county of Dorset, England. A barrier beach over which runs the A354 road connects it to Chesil Beach and the mainland. Portland and Weymouth together form the borough of Weymouth and Portland. The population of Portland is 12,400.