che, which looks like a
western apse with altar in front of it. The roof is a wagon vault
pierced with cross-vaults, but not truly quadripartite, and the caps a
curious combination of badly cut foliage and scrolls and round-arched
arcading. Iron grilles of 1500 isolate the space within the columns
where the sarcophagus stands. There were doorways to the triangular
spaces left between the apse and the rectangular external form, which
were walled up at a later date. The stairs to the crypt go through the
side wings of the Renaissance tribune above with a crookedly set room on
each side, with little windows in the walls, one of which is blocked by
the marble sheeting, while those towards the crypt are also walled up,
showing that the structure is early, and is probably Poppo's. The doors
are of iron, with lions' heads on the south side and man-headed animals
on the other.

The Patriarch Raimondo della Torre (who died in 1299) built the chapel
of SS. Ambrogio and Margherita, which was used as the sepulchral chapel
of the family. It opens to the nave, with two pointed arches with an
oculus above. In the middle of the side wall, between two sarcophagi of
white marble, is that of Allegranza di Rho, second wife of Moschino
della Torre and mother of the Patriarch Gastone. She died July 23, 1300,
and her sarcophagus is the only one of the five in the chapel inscribed.
On the front are reliefs, and on the sloping cover her effigy. One of
those at her side has a figure of a person in subdeacon's dress, with a
key, no doubt Rainaldo della Torre, treasurer to the church and brother
of Gastone. His will of March 31, 1332, gives a precise description of
the monument he wished to have erected to him. There was to be an
archivolt over it, but if it was erected it must have fallen in the
earthquake of 1348, as there are no traces of it. One of red marble,
with a patriarch fully robed, with pallium and mitre, standing on a
dragon between a processional cross and a crozier, with censing angels
on each side of the head, is that of either Raimondo or Pagano. It also
bears a relief of the Annunciation. On the front of another are three
circular plaques with the Agnus Dei in the centre and crosses in the
others; in the spaces between are flatly treated towers, the arms of the
family. In the north transept a sarcophagus front, or altar, stands
against the wall supported on pillars. It has five ogee trefoil niches
with saints within them, and a f