Pennsylvania Castle is a Gothic Revival mansion on the Isle of Portland, Dorset, England.

The castle is Grade II Listed,[1] as is the adjacent gatehouse and lodges, which are now in separate ownership.

[3] The castle, built of Portland stone, was originally a rectangular block until it was extended in the 20th century.

[4][5] Penn discovered the area on one of his trips with King George III, and subsequently chose it for a marine mansion.

[10] The castle was then made available as a holiday home, also catering for weddings, private and corporate functions and other events.