Did you know the Koreans have kept their homes warm for thousands of years with a unique underfloor heating system called ondol? Dating back to the Bronze Age, ondol cleverly channels heat from kitchen fires through stone and brick passages under the floor. This not only keeps rooms toasty even after the fire is out but also helps control pests and improves health by enhancing blood circulation. You can still experience ondol warmth in traditional Korean hanoks, temples, and even some modern hotels.