The remains of Fuerte de la Concepción sit on the headland north of the old town, where the Spanish military positioned it to guard the harbour entrance against pirate attack. Little stands above ground now — the walls were dismantled or collapsed over the years, and what remains is mostly foundation stones and earthworks. But the site itself rewards a visit: the elevated position gives good views along the coast in both directions, and the scale of what was here is legible in the layout of the ruins.
The fort dates from the 18th century, when Spain maintained a network of small coastal fortifications around Puerto Rico to protect its ports. This one never achieved the fame or scale of El Morro in San Juan, but it played the same defensive role on a smaller stage. The headland location is exposed and breezy — a relief on a hot afternoon — and the combination of sea views and Spanish colonial history makes it an interesting stop on a walk along the northern coast.