THE IMPERIAL ATRIUM OF THE THIRD PERIOD. 33 
group but a single structure is evident from their harmony in plan and 
their structural unity. Their striking agreement, in methods of construction 
and in the materials used, with the rooms on the east leaves no doubt as to 
the connection between the two groups. 
The group is modeled after the earlier groups of rooms on the north and 
west,’ not only in its general plan but also in many structural details, such 
as the width of the doors and the size of the small brick pillars, which become 
later so conspicuous a feature of the whole building. The group consists of 
three rooms connected by doors and opening upon a narrow corridor. By 
connecting the newer rooms with the older ones on either side, the whole 
south side of the Atrium was closely united. The corridor is connected 
with the larger one outside by a door 1.77 meters wide and by two lofty 
windows. The door in the rear of the room toward the west may have been 
cut through at this time, though the reason for it is not apparent. The wall 
in the rear of the room into which this door opens, in which are the niches 
for the statues of the household gods, can not have been built later than this 
period,’ since in the next period it was cut off from the room by a second wall. 
Architectural Details: The height of the rooms is not known, but that 
they were lofty is suggested by the height of the walls still standing. In one 
of the rooms,* under a hypocaust of the next period, is a fine pavement of 
opus sectile,> made of giallo antico, rosso antico, Porta-Santa, pavonazzetto, 
and other fine marbles. In the corridor are a few pieces of a similar pave- 
ment. Of the original wall decoration nothing remains, unless it be a dainty 
bit of fresco® on the side of one of the doors. Though no stairs are left, it is 
probable that a second story existed over these rooms, as well as over those 
adjoining. The rooms were probably, from their position, small reception 
or guest rooms. 
Construction and Materials: The construction of the walls of the groups 
both on the east and on the south is of the distinctive type which may be 
recognized everywhere as that of Hadrian.’ In the construction of the east 
rooms the use of a barrel-vault supported by similar smaller vaults on either 
side has been rightly noted by Auer.* His assumption® that this method of 
construction is peculiar to the period following the fire of Nero is, however, 
unwarranted. In both groups the bonding-courses appear regularly and 
are from twenty-one to twenty-eight courses apart. They are made from 
i Plan C;'2-7; 21-23- 7™The use of opus reticulatum inclosed between 
2 The rooms are 4.80 meters long and 5.58, 5.60, bands of brickwork, which is held to be 
3-10 meters wide. The corridor is 3.46 the mark of Hadrian’s construction, is not 
meters wide. a certain test. The type of construction 
3 The construction of the wall is peculiar. The is, however, certain. In this point the 
exact period of its erection is at present new rooms are perfectly in agreement with 
difficult to determine. the Pantheon, the Mausoleum, and the 
4 Plan C, 13 ¢. other more important buildings of the period. 
5 See p. 40. 8 Auer, Der Tempel der Vesta, 6. 
6 See Boni, Not. d. Scavi, 1899, 326f. *Auer, Der Tempel der Vesta, 20. 
