Brownsea Castle, also known historically as Branksea Castle, was originally a Device Fort constructed by Henry VIII between 1545 and 1547 to protect Poole Harbour in Dorset, England, from the threat of French attack. Located on Brownsea Island, it comprised a stone blockhouse with a hexagonal gun platform. It was garrisoned by the local town with six soldiers and armed with eight artillery pieces. The castle remained in use after the original invasion scare had passed and was occupied by Parliament during the English Civil War of the 1640s. By the end of the century, however, it had fallen into disuse.
In 1726 the castle was converted into a private residence by William Benson, despite complaints from the town of Poole. Benson and the subsequent owners extended the original blockhouse to form a country house, landscaping the surrounding island to create ornamental gardens and lakes.
Wikipedia https://en.wikipedia.org/wiki/Brownsea_Castle
Address BH13 7, United Kingdom
Coordinates 50°41'18.308" N -1°57'29.432" E