Santissima Trinità a Villa Chigi is a modern parish church at Via Filippo Marchetti 36 in the Trieste district, just east of the Villa Ada and north of the Villa Chigi. Pictures of the church at Wikimedia Commons. 
The church was designed by Pietro Sanpaolo, and completed in 1979.
The plan is not easy to describe. The design unit is the equilateral triangle, which represents the Trinity. Twenty-four of these are placed together in a hexagon to form the main body of the church, with edges of the hexagon facing east and west. Each side of the hexagon is two triangle lengths long. On the northern triangle length of the north-east edge is attached another, smaller hexagon of six triangles, and a seventh triangle inserted on the southern triangle length of the same side so that there is a straight line along the sides of both hexagons. This line is extended by placing a larger triangle, of four triangle units, on the south-east edge of the larger hexagon. Finally, a lone triangle is attached to this straight line, one triangle length up from the southern corner, so that it protrudes. A glance at the aerial photo may make this clearer.
The edifice itself is low and sprawling with a wide flat roof, and the triangles of the layout are outlined by the seams of the metal roof which follow the concrete beams making it up. The roof is supported by round steel columns, and the low concrete walls are infill. Inside, the same triangular pattern is followed by the unpainted wooden beams of the ceiling, which has boards in between. The interior walls are white, and most of the natural lighting comes from triangular skylights.