Image by James Osmond Getty Images

Nottingham's castle crowns a sandstone outcrop worm-holed with caves and tunnels. Founded by William the Conqueror, the original castle was held by a succession of English kings before falling in the English Civil War. Its 17th-century manor-house-like replacement contains a local-history museum and art gallery. Various cave tours include one through underground passageway Mortimer's Hole, emerging alongside five 17th-century cottages comprising the Museum of Nottingham Life at Brewhouse Yard. The much-photographed statue of Robin Hood stands in the former moat.

In 1330 supporters of Edward III used Mortimer's Hole to breach the castle security and capture Roger Mortimer, the Machiavellian earl of March, who briefly appointed himself ruler of England after deposing Edward II.

A £24 million redevelopment is slated for completion circa 2020. The castle will stay open during the renovations, although individual sections may close for short periods of time – check ahead.