Fort Marion, now a U.S. National Park site, is the oldest existing masonry fortress in the United States. It sits at the harbor entrance at St. Augustine in Florida. The Chapel of St. Mark, which was part of the original fort built by the Spanish, is an excellent representation of Spanish-Catholic commitment to providing a worship space for their garrisoned soldiers.
The Spanish arrived at the present site of Fort Marion in August if 1565 and established the colony of San Agustín in September. Having barely survived attacks from the French and British with their hastily-built forts, on 2 October 1672, the Spanish broke ground on what would become Castillo de San Marcos but it would take 84 years to complete.
In 1740, enough of the fort was completed to offer safety to the besieged garrison and citizens of San Agustín when James Edward Ogelthorpe, from the British colony of Georgia, attempted to conquer it. The fort proved to be impregnable as canon fire from Ogelthorpe’s guns did little damage. During the 27-day siege, “the garrison chapel was the scene of daily Masses, and occasionally marriages and christenings…”1