Princess Anne's Battery is located on Willis's Plateau on the north side of the rock below the Great Siege Tunnels. It was named after the eldest daughter of George II and was first armed in 1732.
It is now home to the only intact battery of 5.25" anti-aircraft guns anywhere in the world. This type of gun was by far the most expensive and complex weapon of the war.
Originally naval guns, the design was modified by the Army so that they could be used as double purpose weapons (anti-aircraft and coastal defence). They became obsolete in the late fifties with the introduction of anti-aircraft missile systems, but the battery was still manned up until the 1980s.
Now part of the World War II Tunnels attraction there is a useful café on site (selling drinks only because of the monkeys) that is open to all comers.