El Morro

Lonely Planet review

A six-level fort with a gray, castellated lighthouse, El Morro juts aggressively over Old San Juan's bold headlands, glowering across the Atlantic at would-be conquerors. The 140ft walls (some up to 15ft thick) date back to 1539, and El Morro is said to be the oldest Spanish fort in the New World. The National Park Service (NPS) maintains this fort and the small military museum on the premises.

Displays and videos in Spanish and English document the construction of the fort, which took almost 200 years, as well as El Morro's role in rebuffing the various attacks on the island by the British and the Dutch, and later the US military. It was declared a Unesco World Heritage site in 1983. The lighthouse on the 6th floor is the island's oldest light station still in use today (although the tower itself dates from 1906). If you do not join one of the free guided tours, at least try to make the climb up the ramparts to the sentries' walks along the Sta Barbara Bastion and Austria Half-Bastion for the views of the sea, the bay, Old San Juan, modern San Juan, El Yunque and the island's mountainous spine. On weekends, the fields leading up to the fort are alive with picnickers, lovers and kite flyers. The scene becomes a kind of impromptu festival with food vendors' carts on the perimeter. You also gain entry to both El Morro and Fuerte San Cristóbal for around US$5 .