The Terme di Caracalla are some of Rome's most massive—yet least-visited—ruins. They're also a peek into how Romans turned "bathing" into one of the most lavish leisure activities imaginable.
Begun in AD 206 by the emperor Septimius Severus and completed by his son, Caracalla, the 28-acre complex could accommodate 1,600 bathers at a time. Along with an Olympic-size swimming pool and baths, the complex also boasted two different gymnasiums for weightlifting, boxing,
and wrestling, a library with both Latin and Greek texts, and shops, restaurants, and gardens. All of the services depended on slaves, who checked clients' robes, rubbed them down, and saw to all of their needs. Under the magnificent marble pavement of the stately halls, other slaves toiled in a warren of tiny rooms and passages, stoking the fires that heated the water.
Taking a bath was a long and complex process—something that makes more sense if you see it, first and foremost, as a social activity. You began in the sudatoria, a series of small rooms resembling saunas. Here you sat and sweated. From these you moved to the caldarium, a large, circular room that was humid rather than simply hot. This was where the actual business of washing went on. You used a strigil, or scraper, to get the dirt off; if you were rich, your slave did this for you. Next stop: the warm(-ish) tepidarium, which helped you start cooling down. Finally, you splashed around in the frigidarium, a swimming pool filled with cold water.
Today, the complex is a shell of its former self. While some black-and-white mosaic fragments remain, you have to use your imagination to see the interior as it would have been, filled with opulent mosaics, frescoes, and sculptures, including the famous Farnese Bull. But for getting a sense of the sheer size of ancient Rome's ambitions, few places are better. The walls still tower, the spaces still dwarf, and—if you try—you almost can hear the laughs of long-gone bathers, splashing in the pools. If you're here in the summer, don't miss the chance to catch an open-air opera or ballet in the baths, put on by the Teatro dell'Opera di Roma (€25–€110; 06/48078400).