Santa Maria Portae Paradisi, also known as
Santa Maria in Augusta, is a 16th century former hospital church in the rione Campo Marizio. The dedication is to the Blessed Virgin Mary, under an unusual title of "Gate of Paradise". The source of the name has also been the subject of some guesswork, with the alternative theories being that the chapel was the "Gate to Paradise" for those dying in the adjacent hospital, or that the name came from the paradeis or garden enclosure of the nearby Mausoleum of Augustus (hence in Augusta).
For reference, a plan of the church is available
here.
The remote origins of the church are surprisingly obscure. The first rebuilding project began in 1519, and was completed in 1523, documented by the epigraph still visible on the façade. Construction was directed by the architect Giorgio da Coltre to the designs of Antonio da Sangallo the Younger and Baldassarre Peruzzi. The benefactor was the Spanish prelate Antonio de Burgos (who died in 1523), with the provision of a funerary chapel. Progress on the scheme continued from 1537, and was finally completed in 1579.
From 1644 to 1654 the church was renovated, except for the façade, following the legacy of the Caccia family, leaving it in the state that it is in now. The architect of the edifice was Angelo Torrone, with the interior fittings being the responsibility of Giovanni Antonio De' Rossi. The restoration involved scooping out the interior of the previous rectangular church and inserting the present round one.