Betchworth Castle is a mostly crumbled ruin of a fortified medieval stone house with some tall, two-storey corners strengthened in the 18th century, in the north of the semi-rural parish of Brockham. It is built on a sandstone spur overlooking the western bank of the Mole in Surrey in England. The ruin is a Scheduled Ancient Monument and is in the lowest category of listed architecture, Grade II, 1.2 miles (1.9 km) due east of Dorking railway station in Dorking and 4 miles (6.4 km) due west of Reigate.