Located within the fortress, this defensive work was built to protect the north curtain wall and bordered one side of the main parade ground, or Plaza de Armas. It was part of a set of fortifications constructed to strengthen the fortress in anticipation of a possible English attack—a threat that loomed after the British captured Havana in 1762. Later, during the period when the National Arsenal was based in Ulúa, this space housed the foundry workshops. Today, the cut and its arched structure are part of the museum’s points of interest.

Throughout its history, the San Juan de Ulúa Fortress Museum served many roles, including that of a prison. Even though the prison and the National Arsenal operated simultaneously in the monument, the area known as the San José Ravelin is especially noted for having been used as a jail.