All those people who say that prisons are too luxurious will be breaking into this Oxford establishment to prove their point. Until 1996 this imposing castle was a working prison, where Porridge and The Italian Job were filmed and felons were incarcerated, two to a room. Now those rooms have been knocked together and poshed up and the castle has become the massive Malmaison hotel.

The 1,000-year-old sandstone building has been kept largely intact, with a gym in the exercise yard, a staff canteen in the old hanging pit, a friendly lady ghost on A Wing and three-inch-thick steel doors to keep you firmly in your place.

The colossal entrance is hung with baronial chandeliers and plushly carpeted. Down in the bar, you are plied with cocktails and dazed by luxury. If you can ignore the posh students who come in to bray about their MAs, and the trendy oldie couples in the restaurant cooing over the cheeseboard, you could become quite institutionalised.

The vaulted dungeons are hypnotically dark, the wine list mesmerisingly without end and the philosophy that "any time is a good time for champagne" strangely bewitching. If you are unfortunate enough to find yourself there on Valentine's Day they even serve up fountains of the stuff with breakfast. Really, it's criminal.

Malmaison, 3 Oxford Castle, New Road, Oxford (01865 268400)