Middle America aka Mesoamerica, also Central America, is the land bridge between North and South America. It extends from central Mexico south to Colombia, through the northwestern border of Costa Rica. This land bridge gave rise to a group of pre-Columbian agrarian Mesoamerican civilizations. Well known names are the Maya, the Aztec, or the Teotihuacán. But there are almost a dozen others, which are less well known. Remains of those cultures are found from 2600 BC to the arrival of the Spanish in 1697. That's approximately 4,000 years before the discovery of the New World by Columbus.
Mexico and several small countries have karst and caves, but they are not well developed for tourists. Tours are general cave trekking tours, and they include a long journey and some walking to reach the cave. In many cases the caves contains spectacular archaeological remains, as they were part of the believe systems of the Mesoamerican cultures.