The Torre de Hércules is the oldest working Roman lighthouse in the world. Built in the 1st century AD and encased in its current neoclassical shell in 1791, it still guides ships through the Atlantic approaches to the Ría de A Coruña. It stands on the rocky northern tip of the peninsula, surrounded by a small park with prehistoric rock carvings and a rose garden.
You can climb to the top for views over the city and, on clear days, far out to sea. The UNESCO designation came in 2009. Allow an hour, and arrive at opening time to avoid queues in summer.
According to legend, the tower was built by Hercules after he slew the giant Geryon and buried his head beneath the foundations. The tower was to stand for as long as the head remained buried -- a story the Romans likely inherited from an older Celtiberian myth about the site.