Portsmouth ( PORTS-məth) is a port city and unitary authority in Hampshire, England. Most of Portsmouth is located on Portsea Island, off the south coast of England in the Solent, making Portsmouth the only city in England not located primarily on the mainland. The city is located 22 miles (35 km) south-east of Southampton, 50 miles (80 km) west of Brighton and Hove and 74 miles (119 km) south-west of London. With a population last recorded at 208,100, it is the most densely populated city in the United Kingdom. Portsmouth forms part of the South Hampshire urban area with Gosport, Fareham, Havant, Eastleigh and Southampton.
Portsmouth's history can be traced to Roman times and has been a significant Royal Navy dockyard and base for centuries. Portsmouth was founded c. 1180 by Anglo-Norman merchant Jean de Gisors in the south-west area of Portsea Island, a location now known as Old Portsmouth. Around this time, de Gisors ordered the construction of a chapel dedicated to St Thomas Becket. This became a parish church by the 14th century. Portsmouth was established as a town with a royal charter on 2 May 1194. The city is home to the first drydock ever built. It was constructed by Henry VII in 1496.