I'm glad I visited La Fortaleza and San Juan Historic Site in Puerto Rico when I did in the fall of 2016, since I learned how beautiful and atmospheric Old San Juan is. This historic city is one of two Spanish built World Heritage Sites in the United States, and includes forts on either end of Old San Juan, most of the city walls, and La Fortaleza, home to the governor of the island. I didn't get to tour the palace, but I did visit both Castillo San Cristóbal, the fort on the east side of Old San Juan, and Castillo San Felipe del Morro (El Morro), the fort on the west side of town at the entrance to San Juan Bay. San Cristóbal offered great views of the city, and was laced with tunnels and batteries to explore. Across town, El Morro's prominent position atop a hill, with the Caribbean crashing into the rocks below, helped contextualize its defensive importance. The walls of both forts were lined with the guard post towers, known as garitas, for which San Juan is famous. The US National Park Service offers informative historical programs at both forts, and I highly encourage a visit. This is particularly relevant now, since Puerto Rico can use as much tourism as possible to help its people recuperate in the aftermath of 2017's devastating Hurricane Maria.

Logistics: La Fortaleza and San Juan Historic Site can be explored on foot, although warning must be given that Old San Juan is rather hilly; a recommended scenic (though cat-ridden) path around the west end of the island provides a good view of the walls from the old gate of the city to the base of El Morro.