There's something bordering on ecclesiastical about the beautifully embellished keep of this castle, built in 1138 and set in the middle of a massive earthwork – unsurprisingly it shares stonemasons with some of East Anglia's finest cathedrals. Castle Rising was also once the home of Queen Isabella, who (allegedly) arranged the gruesome murder of her husband, Edward II. It's 4 miles northeast of King's Lynn. Bus 34 runs here (£1.80, 15 minutes, hourly).