Lydden Spout Battery is a World War II coastal defence battery built in 1941 west of Dover. Originally armed with three 6 inch Mark VII naval guns on Mark V mountings, later upgraded to Mark XXIV guns on the same mountings. Fan Bay Battery to the east of Dover is built to the same plan. The battery is to the south of the current A20. Most of the buildings have been demolished and the emplacements filled with concrete, but the catering rooms survive.