Newcastle upon Tyne (ⁱ/njuːˈkɑːsəl/ in Received Pronunciation, locally ⁱ/njuːˈkæsəl/; often shortened to Newcastle) is a city and metropolitan borough in Tyne and Wear, North East England. Historically the county town of Northumberland, of which it was part until 1974, it is situated on the north bank of the River Tyne centred 8.5 mi (13.7 km) from the North Sea. The city grew up in the area that was the location of the Roman settlement called Pons Aelius, though it owes its name to the castle built in 1080, by Robert (II), Duke of Normandy, "Curthose", William the Conqueror's eldest son. The city grew as an important centre for the wool trade and it later became a major coal mining area. The port developed in the 16th century and, along with the shipyards lower down the river, was amongst the world's largest shipbuilding and ship-repairing centres. These industries suffered decline and closure. Newcastle'e economy includes a place as a corporate headquarters, learning, digital technology, retail, tourism and cultural centre.