These ancient fortifications may have been started in the 5th century, though much of the construction dates back to the 15th century, when the Portuguese strengthened Ceuta’s defenses. A seawater moat helped make these stone ramparts—properly titled El Conjunto Monumental de las Murallas Reales (the Monumental Complex of the Royal Walls)—impregnable to attack. Plenty of English-language information boards help visitors explore the garrison, while the museum contained within the ramparts has fine-art and temporary exhibitions.