Cappella delle Suore Missionarie della Società di Maria is a mid 20th century convent chapel at Via Cassia 1263 in the La Giustiniana zone.
The chapel is in the city of Rome, but in the territory of the diocese of Porto Santa Rufina.
The "Missionary Sisters of the Society of Mary" is an active congregation formally established in 1881 as the female branch of the Society of Mary (Marists) -beware of confusion with the Society of Mary (Marianists).
The Marists had been founded in 1816 at Lyons in France, and took a great interest in missionary activity in the Pacific. The first martyr of Oceania, St Peter Chanel, was one of them. Women were accompanying the missionaries as assistants from the 1840's, and these were the progenitors of the new congregation.
The congregation came under the direct authority of the Holy See in 1931. Like many other such, it built a new Generalate or headquarters in a Roman suburb in the Fifties.
It seems that there was a school being run here originally, but that has now closed. The Generalate is now shared with the "Capuchin Tertiaries of the Holy Family", a Spanish congregation.
The chapel is a charming circular building with a welcome civic presence, facing the convent gate. It is a cylinder with wide vertical stripes in pink brick and white limestone, the rectangular slabs of the latter being laid vertically with narrow gaps in the vertical joins.
There is a saucer dome in the middle of the otherwise flat roof, which is in a red composition. The roof is raised above the top of the cylinder on little brick piers, and the void thus created is occupied within by an octagonal fenestration. Hence, the interior has a saucer dome on an octagonal glass drum.
The single public entrance is approached by a flight of stairs (is there a crypt?). The patio is protected by a porch in the form of an open-fronted horizontal rectangular box, with two thin square concrete support piers supporting the front roof beam. Above, the central stripe in the chapel wall is brick and has a round window. However, the stripes in the main wall do not continue down within the porch the back wall of which is entirely in the limestone slabbing.