Santa Maria in Cacaberis is a lost 12th century (?) parish and confraternity church which used to stand in the Via di Santa Maria dè Calderari. This is in the rione Regola.
The church was first mentioned in the famous list of churches dependent on San Lorenzo in Damaso, which was published by Pope Urban III in 1186. It became a parish church in its own right later in the Middle Ages, but only achieved full independence as such in 1594. This probably entailed obtaining its own baptismal font.
This was the first church in Rome dedicated to the Immaculate Conception, although in the Middle Ages it was also dedicated to St Blaise. Several versions of the name Cacaberis survive from that period: Cacchabellis, Cacabariis, Cacabi. It derives from a dialect word for “copper pot”, and refers to a group of cauldron and saucepan makers who used to do business locally. An alternative name was Santa Maria dei Calderari, which survives as the name of a street, and it was also referred to as in Campocori. This last name referred to an open space where slaughtered cattle had their skins removed for leather making (archaeological evidence for this has survived).
A visitation report of 1560 described the parish as having 64 households, but went on to assert that most of the inhabitants were "Jews and scum, enforcers and informers" (erano gran parte guidei e gente vile, sbirri e spioni). The reference to Jews is odd, because the Ghetto had already been established for five years. Presumably part of the parish territory lay within it.
Perhaps unsurprisingly, the parish was suppressed in the 17th century by Pope Alexander VII (1655-67) and the church given over to the guild of junk dealers (rigattieri). It was later occupied by the guild of materassari (sic -mattress makers?), and by the time of the Nolli map of 1748 was in the possession of the guild of coachmen (cocchieri).
This last guild kept possession, and carried out a thorough restoration in the early 19th century. However, the church was demolished in 1881 during the building the Via Arenula. This was a property speculation, as the church was not on the line of the road.
The site of the church is easy to find, since it was next to an ancient Roman portico which is still there. The latter consists of two weathered Doric columns supporting an undecorated horizontal entablature, and nobody knows what it was originally.
Contrary to the opinion in some online sources, the church's entrance was not in this portico but was immediately adjacent to the left. Here there is now a modern building with four arches, and the right hand one of these marks the church's entrance.
The church was small, and basically rectangular in plan. A square external chapel led off each side near the entrance, and the last bay of the edifice was a sanctuary with a triumphal arch.
According to 19th century guidebooks, the church contained no notable works of art.
There used to be a little street leading up the left hand side of the church to the Via di Maria del Pianto, but this has gone.