Castell de Sant Felip

On the north side of Cala de Sant Esteve, 4km southeast of Maó, the Castell de Sant Felip was originally constructed in the 16th century and, under British control, became one of Europe's largest fortresses. When Spain recovered the island in 1782, King Carlos III had the fort largely destroyed. However, its labyrinth of underground tunnels has remained more or less intact, and can be visited on once- to twice-weekly Spanish- or English-language guided tours from March to November.