Porticus to Vestibulum to Atrium
From the Peristylium we ascend by a flight of steps into the Porticus (B), which is of the Corinthian Order. From this there were doors to two winding stairs, which led to the ground story, in order that the slaves might have access thither, without passing through any of the apartments.
From the Porticus we enter the Vestibulum (C) which was commonly of a circular form (I); and in this Palace it seems to have been lighted from the roof. It was a sacred place, consecrated to the Gods, particularly to Vesta (2), (from whom it derived its name) to the Penates and Lares, and was adorned with niches and statues.
Next to the Vestibulum is the Atrium (D), a spacious apartment, which the Ancients considered as essential to every great house. As the Vestibulum was sacred to the Gods, the Atrium was consecrated to their Ancestors, and adorned with their images, their arms, their trophies, and other ensigns of their military and civil honours (3). By this manner of distributing these apartments, the Ancients seem to have had it in view to express, first of all reverence for the Gods, who had the inspection of domestic life; and in the next place, to teftify their respect for those Ancestors to whose virtues they were indebted for their grandeur. On each side of the door into the Atrium, lie two small rooms, one of which may have been the Cella Ofliarii (E), or Porter's Lodge, which Vitruvius tells us was common in houses of the Greeks, and was placed on one side of that passage by them called Thyrorion: the other was probably what the Ancients named a Tablinum (F), which Pliny mentions as a repository for the archives and records of the family, containing the history of the illustrious stories of their ancestors.
Next: Crypto Porticus