At Libarna the baths were located between the theatre and the amphitheatre, to create a real district for amusement, relax and leisure.
The plan is not known because the area was never investigated in a systematic way. On the basis of the description recorded in the old excavations, one might assume that the complex was monumental and occupied same blocks.
Beside bathing areas, the baths hosted spaces for sport, such as the exercise ground or the swimming pool (natatio), and areas for cultural activities, such as halls for public speaking and libraries.
Only from the second century BC the development of thermal architecture began. Previously bathing was a private matter, to which only a small space was destined. Inside the house there was the lavatrina or latrina, located next to the kitchen, to take advantage of the heat. The term latrina was subsequently adopted to define the restroom.
Basic components of the baths were the dressing room (apodyterium), the calidariun, the tepidarium and the frigidarium, which, however, was introduced later than the other elements. These were rooms respectively provided with hot, warm and cold water. Baths could be public or private.
In Italy, the first baths spread in the South, in the Greek colonies of Sicily (at Gela, Syracuse and Megara Hyblaea baths are attested in the third century BC) and in Campania. The Stabian Baths at Pompeii are of particular interest to follow the evolution of the baths in the peninsula. They feature several phases from the fifth to the first century BC, when two innovations were introduced: the suspensurae (that is bricks allowing to raise the floor in order to heat the room) and the laconicum (a room for steam baths). The terms usually adopted to define these environments derive from Greek, because self-care is traditionally connected to the Greek world.
The first building officially designated with the term thermae in Rome were the Baths of Agrippa (26-19 BC) in the Campus Martius (for the first time a bath complex was to occupy a considerable space within the city and included bathrooms, exercise ground, pool and gardens). However, with regard to the diffusion of technical progress and development of facilities in monumental form throughout the provinces, the true model were the Baths of Nero (AD 64) with their axial and symmetrical plan.
The later works (Baths of Titus, Baths of Trajan, down to the Baths of Caracalla) passed them in the extension and splendour, but did not add anything in terms of conception and organization of the building.