THE IMPERIAL ATRIUM OF THE FIRST PERIOD. 19 
With only a few exceptions, however, they can be restored from the impression 
left in the concrete of the later pillars, which were built in front of them. 
The Republican Altar: The ancient altar,! the remains of which are still 
to be seen in the room at the northeast corner of the Atrium, was at this 
time destroyed. This altar is made of ashes and sacrificial material and was 
surrounded by a narrow gutter. At a very early period it stood probably 
inside a separate precinct, or templum, which was inclosed by a wall. At a 
somewhat later period, possibly at the time of the abandonment of the altar 
as a place of sacrifice, a second wall of opus quadratum’ was built inside the 
precinct wall for the better protection of the altar itself. Of this inner wall 
and the altar inclosed by it but little now remains.° 
Arghitectural Details and Construction: The height of the rooms can not 
be ascertained. That they were lofty may be assumed from the thickness of 
the walls, and the height of the doors which remain. There are no pavements 
left in any of the rooms, and there is no evidence of the use of hypocausts, 
as in the later Atria. All traces of decoration have disappeared, with the 
exception of a small bit of fresco in one room. The large quantity of rare 
marbles, however, which have been broken in pieces for use as filling in the 
concrete foundations of the next period,‘ points to their extensive use as 
decoration in the earlier building. There are no stairs and no traces remain- 
ing of an upper story, though it is probable that one existed.® There is 
beneath the whole Atrium an intricate network of sewers.® No attempt has 
been made to describe these, since the data available are insufficient. 
In methods of construction as well as in the materials used, the Atrium 
is perfectly in agreement with the other buildings of the period of Nero. 
The walls are throughout of concrete faced with brick.’ The outer walls 
are 89 centimeters® thick. The inner walls on the south, where, because of 
the width of the rooms, the vaulting supported by them was heavier, are of 
the same thickness. The inner walls on the north are but 74 centimeters,° 
corresponding to those of the shops in their rear. Bonding-courses of tegule 
bipedales” are not found in any of the walls on the north. They have been 
Plan A, B; plate iv, fig.2. The divinitytowhom Professor Huelsen has suggested that walls of 
the altar was dedicated is unknown. The such thickness would not have been built 
shrine of Aius Locutius lay within the /ucus had there been no upper story to support. 
Vesta. Huelsen, from the description of its Under the careful direction of Commendatore 
position given by Cicero (de Div., 1, 45, 101) Boni, a number of the sewers have been 
locates it however much further to the west restored to their original use. 
along the Nova Via. The worship of the 7 The use of the term brick-walls should be avoided, 
divinity to whom the altar belonged was since none existed in Rome. 
probably continued, since in the wall be- & This measurement, which is equal to 3 Roman 
hind there is found a niche for a statue. feet, is very common in walls of this 
2 The inner wall is of a much later period than the period and later. 
altar itself. *Another common measurement, which is equal to 
3 See plan A, B. 2.5 Roman feet. 
4 See p. 28. 10See p. 3, n. 4. 
