Fortress of San Marko

Fuerte de San Marcos is a stone fortress at 260 meters altitude between San Sebastián and Rentería, featuring a polygonal layout with multiple defense positions. The structure contains exhibition spaces, guard rooms, powder magazines, and an underground water cistern.

The fortification was built in 1888 as part of the Oyarzun Entrenched Camp project to protect Pasajes port and surrounding coastal areas. It was constructed during a period when northern Spain was modernizing its coastal defenses.

The fortress functions as a cultural center and hosts exhibitions about regional military history and defensive architecture. Visitors can observe how these structures shaped the landscape and defense strategies of the era.

The site sits on a hilltop with good views of the surrounding region and is accessible by walking paths. Visitors should be prepared for uneven terrain and stairs, as the fortress is built on elevated ground.

A 530-meter covered pathway leads to a tunnel connecting to the main entrance bridge, demonstrating advanced 19th-century military techniques. These underground connections reveal the sophisticated defense system that was engineered for the era.