Puerto Rico is a unique island with stunning scenery as well as a complex history and fascinating culture. It was part of the Spanish Empire for approximately 400 years and there are many reminders of the long Spanish occupation of the island, the most impressive of which is the fort of San Cristóbal, located in the capital of San Juan. This is regarded as the biggest
There are many caves in Puerto Rico, and the native Taino treated them as the home of their gods. There are also places like this - https://www.harbourlakespr.com/packages/camuy-caves-observatory/rio-camuy-cave-park-2/ and https://media.tacdn.com/media/attractions-splice-spp-674x446/0b/87/61/52.jpg (carved arch and old stone quarry), which suggest the work of a long, lost stone culture, similar to what we see in many places in the world. So you wonder how much tunneling/ancient human-cut stones was there already when the Spaniards arrived.