Baths of Caracalla, just past the Palatine Hill.  This was a massive public baths, with two huge gyms, built between 212 and 216 AD.  A scene in La Dolce Vita was filmed here too. We went here last Sunday, Charlie's last day in Rome.  Charlie is back in Michigan now, after a delayed flight out of Rome that caused him to miss a connection so he was put up overnight in a hotel in Amsterdam.