Take a walk along the sea defence at Littlestone, Kent at low tide and what looks like a 'fort' can be seen sitting in the shallows. It is in fact a part of the Mulberry Harbour constructed for the landings at Normandy during WWII. Amazingly, it is built from concrete.
For the Normandy invasion, Churchill needed a harbour from which to supply troops with weapons and transport. As France was heavily protected, a floating harbour was constructed from sections or 'caissons' of concrete.
Hidden from view by sinking them around the coast, they were re-floated, joined together and towed to the Normandy coast. The plan was a success, but unfortunately many of the sections came loose and beached themselves around the coastline of Kent.
Today, as it is a danger to boats, flags have been put on the corners to show its position at high tide and that is why it resembles a 'medieval fort'.
Littlestone beach is a great place for walking, time on the beach, horse riding, shrimping, all with a little history thrown in! For easy access to the beach, there is parking along the Coast Road (not tarmacked) where it meets the sea wall.