These are some of the concrete caissons used on D-Day and after to form an artificial harbor and piers at Arromanches. The caissons were towed across the English Channel and sunk to form the artificial harbor code-named "Mulberry." The harbor was later wrecked by a storm but part of it can still be seen out at sea and on the beach at Arromanches. Several parts are visible on the horizon just above these beached caissons.