a double arch of considerable magnitude, believed to be that of the
four-headed Janus, the appearance of the structure involuntarily
recalling the celebrated sanctuary of that god in the Forum, with
which, however, it must not be confounded. There is no authority for
calling it the Arch of Janus; we do not know what it was called by the
Romans. In the sides of the piers which support the arch are twelve
niches, apparently intended for the reception of statues. In one of
these is a doorway leading up a narrow staircase to a chamber in the
interior of the building, probably used as a place for business.
This singular building, which in its present condition has a somewhat
quaint appearance, has evidently been intended for a place of sale.
Being erected over the spot where the two roads intersecting the
cattle-market met, it seems to have marked the central point of the
traffic carried on in this space.
It is of white marble, old material re-used, and probably of the time
of Constantine. Domitian erected several arches to Janus, but this is
not good enough for his time.
_By its side is_