THE IMPERIAL ATRIUM OF THE FIFTH PERIOD. 45 
from the corner of the Atrium to the juncture of the Nova Via with the Clivus 
Sacer.’ A similar but smaller arcade was built along the narrow street in the 
rear of the Atrium. 
Architectural Details and Construction: The height of the rooms can in 
no case be determined. In the court are pavements of several periods. Of 
these that of opus spicatum belongs probably to this period,’ though that of 
the coarser black and white mosaic is but a little later. Many of the pave- 
ments of opus spicatum throughout the house are, however, of a later period. 
The pavements of opus sectile made of large slabs of marble, which are found 
in the court and in many of the rooms, are also of a later time. The remains 
of decoration which are found in many parts of the Atrium belong in great 
part to this restoration. The most striking of these remains is the dado of 
marble, with which the court and a number of the rooms? are decorated. 
Above this dado the walls were covered with marble facings or with frescos. 
Traces of both these styles of decoration have been found in various rooms. 
The walls are, with a few exceptions, superimposed on those of the earlier 
periods, with which they agree generally in width. The height to which 
they have been left standing varies from a few centimeters to several metezs. 
The type of construction differs greatly from that of the earlier walls.> The 
tegule bipedales appear, though less regularly than in the walls of Hadrian. 
The courses of brick measure from 2.75 to 3.25 centimeters in width and the 
layers of mortar from 2.25 to 2.50 centimeters. The bricks themselves are 
well burned and of a good quality. They vary in color from yellow to yellow- 
red and are of a coarse texture, resembling most nearly those of the periods 
of Nero and the Flavians. 
Later History of the Atrium: Of the changes which took place in the 
Atrium after the time of Septimius Severus, two only are of importance in 
its development. The first of these, which affected the Sacellum Larum 
rather than the Atrium itself, consisted in the construction of two stairways, 
one a short time after the other, in one of the smaller rooms® connected with 
the Sacellum and in the erection of a thin wall in the rear of the court, by 
which the whole group was separated from the rooms of the Atrium adjoin- 
ing it. In this wall were placed the three niches for statues mentioned 
above.” At some later time another stairway connecting the Atrium with 
the Nova Via was added in the room® at the southwest corner of the cen- 
1 See plate x, fig. 1. 4 The walls of the small rooms on the west which 
2 The pavement was laid on the top of one of the are built from the foundations are but 45 
walls across the middle of the court (plate centimeters thick. 
1v, fig. 1), which were broken down in this For the construction of this period see plate m1, 
period. fig. 2. 
3 Door posts as well as a dado of marble are found Plan E, 44. 
in the exedra. They may have been com- 7P. 25. 
monly used throughout the house. 8 Plan E, 43. 
