Brownsea Castle, also known as Branksea Castle, is prominently located on a small island at the entrance to Poole Harbour. Now a private country house, owned by the John Lewis Partnership, it was originally built as a Henrician device fort to defend the large natural harbour from French attack. 

Brownsea Island was the location of the first Scout camp organised by Robert Baden-Powell in 1907. It is also one of the last safe havens for native Red Squirrels in England.