the name ordinarily given to a four-way arch of
marble, which stands directly over the cloaca Maxima, and probably
marked the line of separation between the forum Boarium and the
Velabrum. It consists of four piers connected by quadripartite vaulting,
and is 12 metres square and 16 high. The arches themselves are 10.60
metres high and 5.70 wide. Round all four sides run two rows of niches
for statues, forty-eight in all, of which sixteen are unfinished. The
keystones of the arches were sculptured, and the figures of Minerva
and Roma are still visible on the north and east sides. The structure
is of late date, third or fourth century,1
and may perhaps be identified
with the arcus divi Constantini in Region XI
(Not., om. Cur.; DAP
2. vi. 261; Jord. i. 2
. 471). For a detailed description of this arch, see
PAS ii. 80
; Toeb. i. 131-135
; ZA 258-261 ; for illustrations, Baumeister,
Denkm. iii. pl. Ixxx. 6, lxxxi. 8; Canina, Edifizi, iv. 253. Cf. ASA 119.
Hulsen points out (Toeb. cit.) that the superstructure, which was
removed in 1827 as mediaeval, probably belonged to the attic (DuP.
pi. 23, fig. 38 and pp. 74, 75); and reconstructs it with a pyramid on top.