Monterreal Castle occupies a rocky promontory that juts into the Ría de Vigo, connected to the mainland by a narrow neck of land. The walls enclose the entire headland — a circuit of about 3 kilometres that you can walk for free, with extraordinary views across the bay toward the Cíes Islands and, on clear days, the coast of Portugal.
The castle itself is now a luxury parador, so the interior is off-limits unless you are a guest. But the walls, towers, and sea-facing terraces are open to all. The walk takes about twenty to thirty minutes at a relaxed pace and passes through a small forest within the enclosure. The views toward the open Atlantic from the western bastions are outstanding, especially in the late afternoon.