In the 19th century, after Maó's 16th-century Castell de Sant Felip was destroyed, Queen Isabel II ordered the construction of a new fortress. The extensive Fortalesa de La Mola was built between 1848 and 1875, sprawling over a promontory of the same name on the northern shore of Maó's bay. There are guided visits in Catalan, Spanish, English, German and French, plus audioguides (€3.50); you'll go rambling through galleries, gun emplacements and barracks. It’s a 10km (signposted) drive from Maó.