Roter Sand Lighthouse, Weser Estuary, Germany

Roter Sand in the open North Sea off the Weser estuary, its red and white bands and turreted gallery rising from a dark caisson foundation. First lit in 1885, it was the first structure built directly on the seabed, a pioneering piece of offshore engineering that took a second attempt after a storm wrecked the first caisson. A newer light took over its duties in 1964, and with the caisson now badly corroded, a plan to move the tower ashore is under discussion, so it is worth seeing in place while it lasts.