Cappella del Monastero Nuovo alle Tre Fontane is a later 20th century deconsecrated (or never consecrated) convent chapel at Viale del Tintoretto 200 in the Ardeatino quarter.
Just north of the Abbey of Tre Fontane (see Santi Vincenzo e Anastasio alle Tre Fontane) is a separate monastic complex, with its own large chapel or church. The style, vaguely neo-Romanseque with a few Modernist hints, looks mid 20th century.
The surreal thing about this is, no-one seems to know (or be willing to say) what it was originally. Some monastic congregation must have made a huge error.
Info.roma calls it Ex-monastero benedettino, implying that the Benedictines built it.
Perhaps the Cistercians at Tre Fontane built it in order to get away from the visitors at the old abbey, and then changed their minds?
Towards the end of the 20th century, the complex was the Italian headquarters of Hewlett Packard, and it is now (2018) owned by a multinational firm called Accenture. Not a lot seems to be going on here, so the complex may be mothballed.
It is virtually certain that the chapel is deconsecrated, if it was ever consecrated in the first place.
The following is based on the complex's view on Google Earth, as the gateway at the bottom of its drive is firmly locked.
The monastery consists of a large church edifice, fronted by a two-storey flat-roofed entrance block. Two cloisters flank the church, both enclosed by three-storey ranges. The right hand cloister, which is smaller, has internal walkways with trabeations instead of arcades, but the larger left hand cloister has external walkways with arcading in narrow arches.
The fabric is mostly rendered in a light purplish pink, with windows framed in white and the first storeys also in white. Some of the roofs are pitched and tiled, but others are flat.
The chapel or church consists of a very long single nave, standing over a ground-level crypt. The nave is not divided externally into bays, nor is there any distinction between nave and sanctuary except the campanile. The roof is pitched and tiled, with a hip at the sanctuary end.
The frontage over the entrance block has a row of five tall and narrow rectangular windows, very close together and with their sills on the roof of the entrance block. Each side wall of the nave has seven such windows, of the same size but spaced further apart and not in the lower end of the nave. The sanctuary has two very tall rectangular windows in its right hand side, running from near floor level to the eaves.
A transverse slab campanile is inserted into the fabric on the left hand side, rising from the roof of the cloister range on that side and terminating in a tiled gable cap over two round-headed bell apertures which are side by side.