The Tour du Guet is a 13th-century watchtower that has served as the main landmark of Calais for over seven centuries. It predates English occupation, predates most of the surrounding architecture, and has managed to survive the various sieges and bombardments that levelled much of the city around it. The tower was originally used to watch for enemy ships approaching across the Channel — a practical role in a city that spent much of its medieval history being fought over.
Today it stands somewhat incongruously in the rebuilt postwar city, a medieval remnant surrounded by 1950s concrete. But it is precisely this contrast that makes it worth a look. The tower is not open to visitors inside, but its presence at the heart of the old town serves as a useful reminder that Calais has a history stretching far beyond the ferry terminal.