Castillo San Felipe del Morro or El Morro is one of Puerto Rico's most well-known sites on the island. Located at the northwest point of the islet of Old San Juan, this castle has a history for being an important military outpost for Spain and for the United States later in both World Wars. To know the importance of the El Morro, let's take a couple steps back to learn how it was first built.
In 1521, Spanish settlers found the Old San Juan. Before the construction of El Morro, the Spanish began the first fortification called La Fortaleza in 1533 (which serves as the governor's mansion today). Then, in 1539, the El Morro's construction began and didn't finish until 250 years later in 1790. During their time in Puerto Rico, the Spaniards used the El Morro to defend the bay whenever enemy ships attempted to enter through there and invade the island. These invaders consisted of the British, Dutch, and even pirates.
In 1898, Puerto Rico and El Morro was changed from the hands of Spain to the United States due to the Spanish losing the Spanish-American War. When the First and Second World Wars broke out, the United States used El Morro actively as a miltary installation and designated it as a part of Fort Brooke. In 1961, the US retreated from El Morro and passed it on to the National Park Service for it to be preserved as a museum. And in 1983, El Morro and the city walls of San Juan were declared as a World Heritage Site by the United Nations.
Today, El Morro is now visited by over two million tourists each year ad greets cruise ships as they sail in and out of the bay near Old San Juan.