El Morro juts out of San Juan harbor beckoning cruise ships just as it used to deter sea attacks. The structure is a hulking six-story fortress built between 1539 and 1589, withstanding two World Wars and several other scrimmages. Now, El Fuerto San Felipe del Morro is Puerto Rico's go-to tourist attraction, both for its extensive history and its outstanding vista of the Atlantic Ocean. You can also walk though the fortress' depths, which include a maze of tunnels, barracks and prison cells.
Admission to El Morro is reasonable, considering its size, and as one Virtualtourist notes, "what I enjoyed the most about visiting El Morro was that we were able to roam around the fort on our own." You'll enjoy exploring more if you wear comfortable walking shoes.
El Morro is one of two forts inside the San Juan National Historic Site. Its sister, the Fort San Cristóbal, is one of the largest Spanish fortresses in the Western Hemisphere. Both sites have seasonal hours; during the summer the Visitor Center is open from 9 a.m. to 7 p.m. and you can hike the trails from 9 a.m. to 6 p.m. Admission is $3 for patrons age 16 and over, $5 if you want to visit both forts.