How did ancient Greeks and Romans use hot springs?

In ancient times, both the Greeks and Romans utilized hot springs as a direct source of geothermal energy for bathing, warmth, and therapeutic purposes.1

For the Romans, these natural springs were often developed into sophisticated spa complexes. A prominent example is the site of Roman Baths in present-day Bath, England, where Romans constructed an extravagant facility around geothermal springs that yielded water at temperatures exceeding 104 °F (40 °C). These establishments served as social hubs where bathers would progress through a series of rooms—including the tepidarium (warm room), caldarium (hot room), and frigidarium (cold room)—to relax and socialize.23

While the Romans are well-known for their engineered thermae, which often used hypocaust systems to heat water artificially, their use of natural hot springs demonstrated an early appreciation for geothermal resources. These sites were frequently associated with healing, and the water was valued for its perceived medicinal properties, a practice that continued to evolve throughout the Roman Empire.3425