This blockhouse was built by Theodosius I, at the same time when doing the finishes of the fortress artillery of the Castle. In the 18th century was reinforced by d. João V, a century after having been demolished after the war of restoration.

This chapel was built in the 16th century, but was badly damaged by the war of Restoration, in addition to having been greatly altered in the Baroque period. The interior is fully lined with Baroque murals, restored in the 20th century. Currently open only to the annual party of the Patron Saint, on Pentecost Sunday.