Caister Castle is a 15th-century moated castle situated in the parish of West Caister, some 5 km (3.1 mi) north of the town of Great Yarmouth in the English county of Norfolk (grid reference TG504123).
The castle had a 100 ft (33 m) high tower and was built between 1432 and 1446 by Sir John Fastolf, who (along with Sir John Oldcastle) was an inspiration for William Shakespeare's Falstaff. The castle suffered severe damage in 1469 when it was besieged and captured by the Duke of Norfolk. The castle, other than the tower, fell into ruin after 1600 when a new house was built nearby.
The castle's tower is still intact and can be climbed by visitors.