This site is built in Dover Castles East ditch in the napoleonic times. It has a clear view overlooking the harbour. The is a samll tunnel, (which is blocked by a gate), that leads down from inside Dover Castle to the ditch.
There is also two post war gun inplacements situated just before the tunnels with two resonably sized rooms that would have held the ammunition.
After jumping into the ditch there is brickwork lining the hole of the ditch until the end where there is a wall with 'arrow slits'. The 1st and largest door takes you into a small corridor with rooms off the sides. When I went one room was blocked by a metal door, this would have led to anouther set of rooms with steps and wartime wires.
The next is a tunnel leads into Dover Castle, with two spiral staircases on both sides. The 1st room on the right leads onto the main tunnel complexes with long tunnels and rooms with fireplaces as well as more spiral staircases.