So I’m supposed to be doing this travel writing thing; supposed to be documenting the things I see in the places I go. But I can’t stalk out a story. I can’t just show up at a historical site, or restaurant, or cultural location, and start to write. The story finds me. It manifests itself anywhere, at any time, and demands to be written. So when I found myself at Castillo de San Cristóbal, one of the forts of San Juan, and a truly recognizable symbol of Puerto Rico, I figured I should probably write something about it. I stood there,…