Santa Maria Assunta e San Michele a Castel Romano is a modern parish church at Via Ettore Janni 31, in the suburb of Trigoria which is to the west of the Via Laurentina south of the Circonvallazione Meridionale. It is part of the Castel di Decima district.
It was completed in 1990. The plan is an irregular decagon, with three sides occupying the entrance frontage and two for each side wall with internal angles (so that the church is waisted). The final three sides are at the altar end, matching the entrance end except that the side behind the altar is short.
The roof is a complicated shape, with several pitches meeting at a point on the church's major axis a little nearer the entrance than the altar wall. Over the entrance is a high triangular gable, with its associated pitches running back. The altar wall has a similar arrangement, except that the angle is more acute. There is a slight gable over each waisted side wall. The eaves overhang these walls substantially, and are supported by concrete pillars. The walls themselves have their bottom halves in pale yellow-brown tile and their top halves in window.
The entrance façade is recessed within the side walls, and has a sheltering canopy provided by the overhanging triangular gable, and the gable itself is occupied by clear glass. There is a horizontal concrete beam between this and the door, and two vertical pilasters supporting the gable. The door itself is in clear glass with an abstract pattern.
The gable over the altar also contains a large triangular window. Externally it is framed by two inverted V's in concrete, one behind the other, which together make up the campanile.