Pendennis Castle is an artillery fort constructed by Henry VIII near Falmouth, Cornwall, England between 1540 and 1542. It formed part of the King's Device programme to protect against invasion from France and the Holy Roman Empire, and defended the Carrick Roads waterway at the mouth of the River Fal. The original, circular keep and gun platform was expanded at the end of the century to cope with the increasing Spanish threat, with a ring of extensive stone ramparts and bastions built around the older castle. Pendennis saw service during the English Civil War, when it was held by the Royalists, and was only taken by Parliament after a long siege in 1646. It survived the interregnum and Charles II renovated the fortress after his restoration to the throne in 1660.

Falmouth is a town, civil parish and port on the River Fal on the south coast of Cornwall, England, United Kingdom. It has a total resident population of 21,797.