Newcastle upon Tyne (RP: /ˌnjuːkɑːsəl əˌpɒn ˈtaɪn/; Locally: /njuːˌkæsəl əˌpən ˈtaɪn/), commonly known as Newcastle, is a city in Tyne and Wear, North East England, 103 miles (166 km) south of Edinburgh and 277 miles (446 km) north of London on the northern bank of the River Tyne, 8.5 mi (13.7 km) from the North Sea. Newcastle is the most populous city in the North East and Tyneside the seventh most populous conurbation in the United Kingdom. Newcastle is a member of the English Core Cities Group and is a member of the Eurocities network of European cities. Newcastle was part of the county of Northumberland until 1400, when it became a county itself, a status it retained until becoming part of Tyne and Wear in 1974.