UNESCO World Heritage Site Durham Cathedral was voted Britain's favourite old building in a 2001 BBC poll, and it's easy to see why. A Norman marvel, you'd never guess it was 900 years old such is the impeccable architectural details with breath-taking columns and stone vaulting. Be sure to visit the shrines of St Cuthbert and the Venerable Bede while you're there.
Built in 1072 by William the Conqueror, Durham Castle is a citadel unrivalled by any other, but since 1832, the castle has been a college of Durham University, so students act as guides during term time, pacing along the maze of halls and galleries and oak staircases.
When the students go home for summer, the castle becomes a hotel, with majestic stonework walls offering an opulent night's sleep followed by a breakfast in the Great Hall. A good sleep will set you up for the fun of the covered market with its list of the city's freemen, including Bishop Desmond Tutu and football manager Bobby Robson, above the fishmonger.
Or you might want to head to one of the museums or exhibitions, Durham University's Oriental, Durham Light Infantry, with one of the best military exhibitions going, and the Durham Art Gallery, with its world-class exhibitions.