It took the Spanish government nearly three decades, from 1848 to 1875, to build this military fortress. It sits in a prime spot, at the tip of a peninsula overlooking the mouth of Mahón’s deepwater harbor. Visitors pass beneath the imposing Queen’s Gate to enter La Mola, also known as the Fortress Isabel II. Once inside, they can see the barracks, emplacements with Vickers-Armstrongs artillery guns, the Princess Tower, the prison and the Queen’s Water Cistern. The peninsula, also a bird sanctuary, offers stunning views of the coast.