Many people don’t know that Budapest is built on top of large swaths of limestone, which the water from its thermal springs has carved out into a beautiful cave system. Not all of them are accessible to inexperienced cavers, but the Palvolgyi cave system, located in the Duna-Ipoly National Park, offers two tour options with no prior caving experience needed: a 45-minute easy walk along an artificial footway, or the 3-hour adventure version, where you’ll often find yourself climbing and crawling (helmets, lights, and overalls provided). The latter, as you might imagine, is not ideal for the claustrophic! Budapest cave tours are limited to guests between the ages of 6 and 55.