On the sides of the octagonal room there were two apartments: the "room of Achilles in Skyros" and the "room of Hector and Andromache", judged from their paintings. The side spaces served both as passageways and as buttress elements for the dome; These spaces were accessed through large openings surmounted by brick courses. This was probably one of the models from which the famous dome of the Pantheon drew inspiration: it is in fact an early example of the use of the cementitious technique, which had been developed by the Romans from the second century BC for the development of large and articulated interior spaces.