With its sturdy stone walls and narrow entrance the imposing gateway into Canterbury was an ideal prison. Used as a place to incarcerate, display and dispose of criminals between the 15th to 19th centuries; it would have been a sight to behold.
On the side of the wall is an information board describing The Westgate:
'The Westgate, built in c. 1380 on the site of a Roman gate, is one of the finest surviving medieval gateways in Britain and one of the first major fortifications to incorporate facilities for guns. Though built as a fortification against the French during the Hundred Years' War, the gate was used as the city prison until 1829. The Westgate now houses a museum and small exhibition illustrating the city defences. From the battlements there are superb views of the suburb of St Dunstan's to the west, the line of the walls extending north and south and the main street of the town to the east.
A more detailed history of the gate can be found through the passageway on the right, beyond the river.'
The board shows a picture of the gate in 1870 and a map of the city walls.
Wikipedia goes on to describe the gate in more detail:visit link
'The Westgate is a medieval gatehouse in Canterbury, Kent, England. This 60-foot-high western gate of the city wall is the largest surviving city gate in England. Built of Kentish ragstone around 1379, it is the last survivor of Canterbury's seven medieval gates, still well-preserved and one of the city's most distinctive landmarks. The road still passes between its drum towers, and there is just enough room for a double-decker bus to pass beneath. This scheduled monument and Grade I listed building houses the hundred-year-old West Gate Towers Museum.
It is expensively faced in coursed ashlar of Kentish ragstone. It has battered plinths to the drum towers, battlements, machicolations and eighteen gunloops: a high number for a gateway, and among the earliest gunholes in Britain. The gunloops would have been added by the beginning of the fifteenth century. It had a drawbridge over the Stour, a portcullis and wooden doors.
The gateway has three floors. The ground floor was designed so that the gateway and vaulted passage had entrances to the towers on each side. Each tower had a ground-floor room with fireplace and four gunloops. The north tower's ground-floor room had a spiral staircase to upper floors. The first floor contains a large room with fireplace and, originally, the portcullis mechanism over the vaulted entranceway. This room had doors to the upper room of each tower, each with fireplace and three gunloops, and a northern door to a spiral staircase leading to the roof. Repairs were carried out due to an invasion scare during the 1470s and 1480s. In 1491 or 1492 a large, two-light, transomed, perpendicular east window was added to the large first-floor room, with a view towards the cathedral and along St Peter's Street. The roof over the large first-floor central room has a battlemented parapet walk, originally with access to the tops of both towers and machicolations, as well as to the two low chambers, each with two gunports, in the tops of both towers. This part of the tower was less well-built than the lower storeys, either due to haste during the Peasants' Revolt or because it was built later. In 1793-1794 the hall over the gate was split into three and the present square lantern added to the roof, along with the wooden doors and cell linings which are visible today; the cost was £400.
The city walls joined the gateway at the back of the drum towers, but this part of the wall was removed in the nineteenth century. Following this, in 1823-1829, a jailer's house was built on the north side, and this became a police station and is now a music school. The disused iron bridge which connects the Westgate with the music school dates from this time. Contemporary with this work was the building of St Peter's Place on the south side of the Westgate, along with passages around the Westgate and a new road across the Stour, to cope with increased traffic, which has been damaging the arch of the building for one hundred and fifty years.
At the end of the 19th century the Westgate was a temporary repository for the city archives until the museum was opened in 1906. It is the largest surviving city gate in England.
In 1453 Henry VI permitted the Mayor and Commonality to keep a jail at the Westgate, so the building was Canterbury's prison from the 15th to the 19th century, while Canterbury Castle was the county jail. After repairs to the Westgate and jail in 1667, a pound was built on the north side; this is now gone, but Pound Lane remains. The guard rooms, heavily wood-lined in the eighteenth century, became cells for both debtors and criminals, and the room over the arch became the condemned cell with the portcullis now laid on top. Until 1775 there was a grated cage in the prison gateway, where certain prisoners were allowed to beg for alms and speak with passers by. Capital punishment was normally the gallows, plus the stake at Wincheap for religious martyrs in the time of Queen Mary.'