Oxford Castle

Built during the Norman conquest and destroyed during the Civil War, the remains became part of Oxford Prison. In the 1970s, the inmates held a seance and afterward, poltergeist-like activity was experienced, and a shadowy figure going up the stairs was observed. The crypt is the oldest part of the castle, and it is said that a spectral monk frequents the area. He is reported to be ill mannered and has been heard swearing. There are also claims that Empress Matilda has been seen on the stairs wearing a white cape; she lived here in the 12th century but fled in the night when the castle was besieged by King Stephen, her cousin.

Update 28/7/21: I contacted the Castle and Prison via Facebook and they directed me to pages on their website from 2016 in which staff told of their experiences. A team member told of smelling alcohol in the crypt where Brother Bernard brewed his alcohol; there have been stories of this perpetually drunken monk being seen and the corner of the crypt is named after him. Another staff member experienced doors open and closing - one with an "almighty crash", while another heard a woman laughing from inside a cell after the building had been vacated of visitors. A guide dog belonging to a guest reacted very strangely at the base of St George's tower - whining and growling before rushing back upstairs to the shop area.

Link: Oxford Mail