The Tower of Hercules Lighthouse, located at the entrance of La Coruña Harbor in Galicia, Spain, has been in use since the late first century AD. The only fully preserved Roman lighthouse that is still used for maritime signaling, the Tower of Hercules is a UNESCO World Heritage site. The lighthouse was built on top of a 187-foot-tall rock jutting into the Atlantic Ocean. The lighthouse was restored and augmented in the 18th century. You can tour the lighthouse every day of the week.