What's a good 3-day itinerary for San Juan?

Old San Juan sits on a narrow islet, about 7 blocks wide, connected to the mainland by three bridges. Start at Cuatro Sombras before the heat builds. The cortadito here is strong and sweet, served from a counter in a room barely bigger than a closet. Walk north to El Morro by 9 AM. The wind off the Atlantic is constant up here, strong enough to send kites wheeling over the sloping lawn. Inside, the fortress galleries run dim and cool, a relief when the humidity outside hits 82%. At La Mallorca for lunch, the mallorca sandwich sounds wrong, sweet bread with ham, cheese, and powdered sugar, but it works. The Cathedral of San Juan Bautista dates to 1529 and holds the marble tomb of Juan Ponce de León. The late afternoon belongs to Paseo de la Princesa, the tree-lined promenade that runs 600 metres along the southern bay wall.

Day 2 moves 4 kilometres east to Condado and Santurce. Condado Beach is swimmable by 9 AM, the sand coarser than you might picture, more like crushed shell than powder. The September water is warm enough to stay in for an hour without thinking about it. By 11 AM, walk south into Santurce to the Museo de Arte de Puerto Rico. Lunch belongs to La Placita de Santurce, a working produce market during the day. On Thursday and Friday nights, the same square fills with hundreds of people drinking Medalla Light from plastic cups under string lights. That said, the daytime version is calmer and better for a 1 PM sit-down. The whole fried snapper with tostones at José Enrique's is the strongest meal on this itinerary, the plantain crunch against the soft white fish. By mid-afternoon, walk Calle Cerra for the Santurce murals. The quality varies, but a few pieces run 3-4 storeys high.

Day 3 heads 15 minutes east by rideshare to Piñones, a coastal strip along Route 187 lined with mangrove and coconut palms. Rent a bicycle at the trail entrance. The paved path runs east along the shoreline past tidal channels, with salt air thick enough to taste on your lips. Stop at the open-air kiosks for alcapurrias. These deep-fried fritters, stuffed with crab or ground beef, come out of the oil crackling and too hot to hold. By early afternoon, head back to Ocean Park, the residential beach between Condado and Isla Verde. The waves tend to be gentler than Condado's, and the 1-kilometre shoreline sees fewer vendors. Kasalta bakery is the neighbourhood breakfast institution. Order the quesito, a flaky cream-cheese pastry still warm from the oven. Dinner at Vianda in Santurce closes the trip with a tasting menu built on local produce and seafood.

September in San Juan currently runs warm, with a heat index near 32°C by noon and afternoon showers that pass in 20 minutes. Pick up a packable rain layer at any pharmacy on Ashford Avenue in Condado. Puerto Rico uses the US dollar and American cell networks, so a stateside phone plan likely works without roaming charges. No passport needed for US citizens. Uber and Lyft both operate across the metro area, and a ride from Condado to Old San Juan costs $8-12. The total walking distance across three days is about 19 kilometres, plus the Piñones cycling stretch.