One of the things that the Ancient Romans were obsessed about were their public baths. The baths formed an essential part of the socialising ritual in their lives and both men and women would spend significant amounts of time in the baths.
The baths were not just about showering but resembled more the spas of today. Any standard bath in Ancient Rome would have the following set of rooms
The Apodyterium or the changing room- Most often the first room that one encountered, a typical apodyterium is where people undressed before getting into the other portions of the Bath. This section would often have benches or niches where people would leave their clothes and belongings (along with a helpful slave who would look after them maybe).
You then moved through the warm rooms (the tepidarium) into the hot room (the caldarium) and then the frigidarium (the cold room). You would also find a natatio- the swimming pool (I once read an article on how filthy these could have been- gulp!) and also palaestra – the exercise courts.
What differentiates the baths of Caracalla from other baths in all parts of the empire is the sheer size of the construction. At its peak the baths could accomodate more than 1000 people simultaneously. It is also estimated that it took over 6 years to construct the baths. Just the Caldarium in the baths of Caracalla was a huge domed structure- the remains of which dwarf everything around them even today.
The bath complexes also had shops, libraries and so on making them a place where people got together and exchange information.