Standing on the southern side of the entrance to Mahón harbour, this 18th-century fort offers guests an insight into military engineering in the 18th century and the necessity of the fort at a time when Mahón harbour was undoubtedly one of the most coveted in the western Mediterranean by foreign powers.

It takes its name from Sir John Churchill, Duke of Marlborough, the most prominent British General of the time and a forefather to Sir Winston Churchill, Britain's Prime Minister during World War II.

The small fort would once have been equipped with several artillery guns for defending against possible enemy attack. Nowadays, there's an exhibition montage integrated in the enclosure that explains the history of the fort, the turbulent 18th century, and the legacy left by Britain in Menorca. On the upper levels, there's also exceptional views over the historic area of the harbour.