The fortifications of Kingston upon Hull consisted of three major constructions: the brick built Hull town walls, first established in the early 14th century (Edward I), with four main gates, several posterngates, and up to thirty towers at its maximum extent; Hull Castle, on the east bank of the River Hull, protecting Hull's river harbour, constructed in the mid 16th century (Henry VIII) and consisting of two blockhouses and a castle connected by a curtain wall; and the later 17th century Citadel, an irregular triangular, bastioned, primitive star fort replacing the castle on the east river bank.
The town walls were demolished and replaced with the town docks over approximately 50 years from the 1770s, the Citadel was demolished and the site turned over to shipbuilding and dock activities in the 1860s.
The early Hull is thought to have been surrounded by a ditch, in the 14th century, construction of walled defences began. During the reign of Edward I, in 1322 the town gained the right of murage for five years; in 1327 permission to crenallate was granted – including the construction of a fortified wall and houses. Additional grants of murage were given in 1341, and in 1348. The circuit of walls is thought to have been completed by sometime around 1356, built primarily of brick. The plan of the fortified town has been said (Parker, 1853; Viollet-le-Duc, 1856) to be similar to that of the contemporary Bastides of France, in particular Libourne, also founded under Edward I.
When built the walls stretched from the west bank of the Hull to the bank of the Humber estuary. By 1640 there were with barbicaned gates constructed across a moat at either end; Northgates near the River Hull, and Hesslegates near the Humber. There were intermediate gates at Beverley Gate and Myton Gate. There was also a wall against the Humber, from Hessle Gate to the confluence of River Hull and Humber estuary at South End; on this part of the wall a gate (Water Gate, or Mamhole gate.) gave access to the Humber, by a small piece of land known as the Mamhole, used as the town dump amongst other purposes. Except at the mamhole the south walls were built up to the banks of the Humber. There were no walls on the bank of the River Hull, and soft ground at Northgates near the river bank prevented the walls being contiguous up to the river bank, in 1585 the fortifications at this gap were improved; a mud wall was constructed, and in 1630 a earthen wall with brick facing and a palisade was built.