The Tower of Hercules is the only Roman lighthouse which, since its origins up to the present, has been performing its original function: being an aid to navigation for ships crossing the Atlantic corridor. Although the exterior is from late 1700s, inside is hidden a Roman lighthouse ordered by the Emperor Trajan in the early 2nd century. Since 2009, it has been included in the list of World Human Heritage and it has the privilege to be the oldest roman lighthouse that is still working in the world.