The Westgate is one of only two surviving mediæval gatehouses into the city of Winchester, the former capital of England.
Although in its present form the gatehouse dates from the 12th Century with modifications in the 14th Century, it has Roman and Saxon origins and since 1898 has been used as a museum.
Winchester was one of only two cities in Hampshire to be completely defended by walls.
To ensure that it remained defensible, the gatehouse was built to be strong enough to withstand attacks from enemies who could hold higher ground nearby. Most of the ground floor is dominated by the arched passageway through which all traffic entered and left Winchester.
To the north of the main passageway a pedestrian walkway has been cut through the gatehouse.
This was originally part of a two-storied Porter's Lodge.
The porter would be responsible for opening and closing the gate, not only in time of danger but also after the curfew bell had been rung, as well as collect tolls on goods entering the city.
Above the archway on the first floor is the main chamber, which housed the winch for the portcullis and from which the Westgate could be defended using the gunports.
This chamber has had various uses over the years and is now a museum.
Above the first floor is the parapet or battlement level.
The Romans under the Emperor Claudius invaded Britain in 43AD and one of the first Roman settlements was at Winchester.
In approximately 70-75 AD the Romans enclosed Winchester, known as Venta Belgarum, 'Marketplace of the Belgae people', with a defensive ditch on the north, west and south sides, diverting the River Itchen to defend the east.
This enclosed a roughly rectangular area; on the western side, halfway down, the wall projected out to enclose an area of high ground on the south of the city.
Its ditch and bank were later strengthened by the building of a stone wall around 180-200AD.