Set in parklands designed by Lancelot 'Capability' Brown, the imposing ancestral home of the Duke of Northumberland has changed little since the 14th century. It's a favourite set for film-makers and starred as Hogwarts for the first couple of Harry Potter films. The interior is sumptuous and extravagant; the six rooms open to the public – staterooms, dining room, guard chamber and library – have an incredible display of Italian paintings, including Titian's Ecce Homo and many Canalettos.
Various free tours include several focusing on Harry Potter and other productions that have used the castle as a backdrop, including British comedy series Blackadder and period drama Downton Abbey.
For the best views of the castle's exterior, take The Peth to the River Aln's northern bank and follow the woodland trail east.