A vaulted chamber under Westcroft (see
TQ2450 : Westcroft).
It is thought to date from around the 15th century, as the basement of a "market house", this being the original market site, at the point where Nutley Lane met Slipshoe Street. This house may also have served as a court house, with the undercroft used as a prison. At some point the building was demolished, and the undercroft filled with rubbish.
The undercroft was eventually rediscovered in 1922 and has now been restored.
It is designated a scheduled ancient monument.