Castillo San Felipe del Morro at San Juan National Historic Site

San Juan National Historic Site in Puerto Rico preserves two massive fortresses built by the Spanish on the western end of San Juan Island to protect the original settlement of San Juan, today known as Old San Juan. Castillo San Felipe del Morro, more commonly known as El Morro, sits at the very western tip of the island. It was built to keep enemy ships from entering San Juan Bay. Castillo San Cristóbal, the larger of the two forts, is a little less than a mile to the east of El Morro. It was built to protect the town from a land invasion. Also part of the park are Fort San Juan de La Cruz (El Cañuelo), the San Juan Gate, and most of the original city wall around Old San Juan.

The Spanish were the first of the European super-powers to reach the Americas when Italian Christopher Columbus led a Spanish-financed expedition in 1492. Because Puerto Rico was the first major island that European ships came to when sailing to the Americas from the west coast of Africa, the typical route used at the time, it was strategically very important.

In 1508, the Spanish, led by Juan Ponce de Leon, conquered the local Taino people and established a settlement on the Puerto Rican mainland across the San Juan Bay from modern San Juan called Caparra (modern Guaynabo). Over the next decade, the drawbacks of Caparra gradually became evident. Beginning in 1519, the Spanish began moving across the bay to the island that was at the time called Puerto Rico, and Caparra fell into ruin. In 1521, the new settlement was renamed Ciudad de Puerto Rico de San Juan Bautista, and that is the date officially recognized as the founding of San Juan.

Given the importance of Puerto Rico, and particularly the deep water port at San Juan Island, it was in Spain’s best interest to protect it from the other European powers that were soon coming to conquer the Americas. Construction of the very first fort on the island, La Fortaleza, began in 1533 and was completed in 1540. The fort was far from optimal, and it was captured by the English in 1598 and the Dutch in 1625. In the mid-1800s it was converted into the governor’s house, and it continues to be the governor’s house today. While it is not part of San Juan National Historic Site, it is open for tours.

Construction on the original El Morro began in 1539. This fort was much smaller than the one standing today, and while it survived an attack by the English in 1595, its shortcomings led to its capture during a second English invasion in 1598. Luckily for the Spanish, an outbreak of dysentery two months later forced the English to abandon Puerto Rico, leaving them in control once again.

After being overhauled in the early 1600s, El Morro withstood the 1625 Dutch invasion. Subsequent renovations and improvements continued for another 200 years. Most of what stands today stems from work done between 1760 and 1790.

As a result of the Dutch attack, the Spanish decided to expand its fortification of San Juan, and in 1634 construction began on both Castillo San Cristóbal and a wall around the city. San Cristóbal was much larger (acreage-wise) than El Morro. In fact, it is the largest fortification ever built by the Spanish in the Americas. Despite construction beginning later and the fort being larger, it was actually completed a few years earlier than El Morro in 1783.