St Nicholas of Tolentino in the Gardens of Sallust is a 17th century collegiate and former conventual church in the rione Trevi. It belongs to the Armenian Catholic Church, one of the Eastern Catholic Churches in communion with the Holy See. The Pontifical Armenian College, the Armenian seminary in Rome, is located next to the church and is in charge of it. The dedication is to St Nicholas of Tolentino, a 13th century Augustinian friar.
For reference, a plan of the church is available here
The church and convent were founded on a country site here by a group of Discalced Augustinians in 1599. A rebuilding project was begun in 1620, originally by Bonaventura Cherubino, architect from Spoleto, and Carlo Buzzi. Enough construction was done for the church to be opened in 1624.
However, money was very short and work continued slowly until Camillo Pamphilj, the nephew of Pope Innocent X, and his wife Olimpia Aldobrandini assumed responsibility for the reconstruction of the church. The prince selected Alessandro Algardi to supervise. He was involved until going to Spain in 1650.
In that year, Martino Longhi the Younger did some work on the almost completed church, including on the sacristy, choir and decorative elements. Finally, in 1651, Giovanni Maria Baratta finished the structure, including the impressive façade. Progress on the decoration of the interior slowed down, but Baratta continued with the assistance of Ercole Ferrata and Domenico Guidi. In 1670 Francesco Buzio from Milan altered the façade and high altar. The church was only consecrated in 1685.
The convent was requisitioned by the French military in 1798 for the duration of the Napoleonic period. In 1883 the complex was granted to the Armenians as a seminary college. This has been their headquarters in Rome since then. The old convent was demolished in 1939 to make way for one of Mussolini's roads, the present Via Leonida Bissolati. The present college buildings are on the site of the former gardens.