American Treasure: Castillo San Felipe del Morro

Words: Aleena Siddiqui
Photo Credits: felixairphoto, VisionsbyAtlee, and Sean Pavone

Background
Castillo San Felipe del Morro ("The Promontory Castle of Saint Philip"), or El Morro ("The Promontory"), is a colonial fort built by the Spanish in America. It was commissioned by King Charles I of Spain and built in honor of King Philip II. Its construction began in 1539 and wasn't completed until 1787. In the late 1500s to early 1600s, the structure was transformed. Juan Bautista Antonelli and Bautista Antonelli, two Italian engineers, designed the fort to hold out against cannon fire. In the late 1700s, two Irishmen sent on behalf of the Spanish, Colonel Thomas O'Daly (Chief Engineer) and Alexander O'Reilly (Field Marshal), made improvements to Puerto Rican fortifications and troops. The final significant alterations made to El Morro were completed by O'Daly. The six-level structure has 18 to 25-foot-thick walls and stands on a hill that is 140 feet high. Located in Old San Juan, Puerto Rico, the fort protects the Bay of San Juan at its entrance and faces the Atlantic Ocean. It was designed to target and fire at enemy ships. Its location was strategic, given that it stands near what was thought to be one of the best harbors in the Caribbean. By the time El Morro was complete, it was the most feared Spanish fort and considered to be unbeatable.

Attacks on El Morro
In 1595, when the fort was still incomplete, English privateer Sir Francis Drake attacked San Juan. Drake was known at the time for his attacks on Spanish ships and settlements across America. Due to strategic errors on his part, as well as the resilience of the defenders, El Morro was victorious. The attack was carried out in an attempt to weaken Spain’s power in the New World. However, this victory helped prove El Morro’s defense capability. A 1598 attack by the Earl of Cumberland, George Clifford, resulted in El Morro’s defeat. Clifford learned from Drake’s failure, preying on the landside of this structure. This area of the fort was considered its weak spot. As a result, the English obtained control over Puerto Rico. However, this only lasted for two months, as a dysentery outbreak occurred. In 1625, during the Eighty Years’ War, the Dutch attempted to take over the fort. This effort resulted in their defeat, and after 21 days, they burned the city and retreated. During their 1797 attack on Puerto Rico, the British targeted El Morro, which helped protect the city during this time. This was part of their third and final invasion of the city during the Anglo-Spanish War.

The Fort's Downfall

The technological advancements that occurred during the Industrial Revolution transformed how nations engaged in conflict. By the time the Spanish-American War of 1898 took place, El Morro was no longer able to serve its purpose due to these major changes in technology. Rear Admiral William T. Sampson commanded the U.S. Navy during the bombardment of San Juan. This occurred on May 12, 1898, and was done with the intent to establish naval dominance in this geographic location. However, the fort proved unable to withstand the powerful technology utilized by the Americans. The Spanish-American War was significant, as Spain no longer ruled over the Americas, and the United States rose as a world power. Throughout both World Wars, El Morro was utilized as a United States military base. When World War I occurred, El Morro was used to monitor naval activity, serving as a lookout point to identify enemy submarines and ships. During this war, the structure was also utilized for military communications. Anti-aircraft guns and a bunker were among the additions made to the structure during the Second World War. However, it was apparent that the fort was outdated for its initial intent.

El Morro in the Modern Day

In the late 1940s, El Morro transitioned from a military site to a historic landmark. In 1949, under the National Park Service, the fort became a new addition to the San Juan National Historic Site, which was established the same year. Another structure included on the site was Castillo San Cristóbal, an additional military fortification. The National Park Service made extensive efforts to restore and preserve El Morro. The organization also created educational programs surrounding the structure. In 1983, El Morro became a UNESCO World Heritage Site. This designation furthered global awareness surrounding the structure, resulting in increased tourism. Today, it is among the most popular tourist attractions in Puerto Rico. El Morro serves as a significant representation of the island’s history and culture, embodying the Spanish Empire’s impact on the New World. It also showcases a combination of modern engineering and medieval architecture. Overall, the site of El Morro will allow future generations to celebrate its rich Puerto Rican heritage while recognizing the structure as a longstanding symbol of resilience.

American Treasure: Castillo San Felipe del Morro

About: American Treasure

MASONRY MADNESS®: Celebrating Skill, Speed, and the Next Generation of Masons

STABILA Elevates Craftsmanship Supporting SPEC MIX 500 and World of Concrete

GEN NXT: Austin Cataldi

Outreach Outlook: Launching Into 2026 With Purpose, Innovation, and National Momentum