These are the heavily vandalised remains of The Royal Naval Arms Depot on Milford Haven docks. Built between the wars, it was finally closed in the 1980s with the loss of nearly 180 jobs. Today it stands abandoned and in very poor condition.
Lots still remain for the explorer though including a giant abandoned running track in the main storage shed, some nice mine storage tunnels cut into the rock of the hillside and a cool jetty.
Once owned by the oil company Gulf, the site is now empty and awaiting demolition