What's the must-see thing in San Juan?

El Morro sits on a rocky headland where the Atlantic meets San Juan Bay. Construction started in 1539 and continued for over 200 years. The lowest battery sits close enough to the surf that you can feel salt spray on your face during high tide. The interior is a maze of ramps, not stairs. Your footsteps echo off walls that are 5 metres thick in places. The lighthouse at the top, rebuilt after the 1898 American bombardment, is still the oldest on the island. Morning visits work best. By noon the exposed ramparts reach 32°C with no shade, and the upper batteries fill with tour groups. Your ticket covers both El Morro and Castillo San Cristóbal on the opposite end of Old San Juan, valid for 24 hours.

Between El Morro and Old San Juan's residential grid, a wide grass field slopes toward the Atlantic. You might see families from across San Juan flying kites here on weekends. Below the fortress walls, the Santa María Magdalena de Pazzis Cemetery perches on the cliff edge. It was founded in 1863 and costs nothing to enter. Hundreds of white marble crypts stack against the sea wall, salt-corroded and tangled with frangipani. You can hear the waves hitting the rocks 30 metres below. From the cemetery gate, Calle del Morro leads south into the colonial district in about a 10-minute walk.

La Fortaleza, the governor's official residence since 1533, is the oldest executive mansion in continuous use in the Americas. Free tours run Monday through Friday and stop accepting visitors at 3:30pm. The blue-and-white facade on Calle Fortaleza is the photograph everyone takes, though you'll find the interior courtyard, with its cool tile floors and the soft echo of a wall fountain, is the real reason to step inside. Nearby, the Cathedral of San Juan Bautista dates to 1529. That makes it the second-oldest cathedral in the Western Hemisphere. Both stops take under 30 minutes each.

Start at El Morro by 9am. Walk south through the cemetery and along Calle del Morro to reach La Fortaleza by 11am, then the Cathedral before midday heat peaks. Old San Juan is compact, roughly 7 blocks wide and 15 blocks long, so the whole loop takes about 3 hours at a comfortable pace. The blue cobblestones on Calle San Sebastián get slippery after the afternoon rain that falls most days in September, so wear shoes with grip. Mind you, the rain only lasts about 20 minutes. Duck into any bar on Calle San Sebastián, order a Medalla Light for $3, and wait it out.