Church of the Holy Trinity of the Mountains

The Basilica of Sant'Andrea delle Fratte was built between 1653 and 1662 but a church already existed on the site in the 11th century. The Baroque reconstruction of the 17th century is the work of Francesco Borromini, but the façade dates back to 1862. The church is the place where the famous conversion of Alphonse Ratisbonne (1814-1848) took place.

The church of Sant'Isidoro a Capo le Case, part of a Franciscan complex, is one of the two Irish national churches. The church and monastery were built between 1622 and 1672, when Spanish Franciscan descalceati (Discalced) arrived to found a convent for their countrymen and built the church which they dedicated to the new Spanish saint. A few years later, the church and convent came under the authority of Irish Franciscan monks, fleeing their country under the persecution of the English Protestants.

All Saints' Church was built between 1882 and 1887 on a former convent for the Anglican community. The famous English architect George Edmund Street (1824-1881) drew up plans to build a new church with an adjoining vicarage. George Edmund Street died in 1881 and his son Arthur Edmund Street took over the supervision of the project. The steeple, which was never completed at the time of construction, was added in 1937. The church is now also served by the Old Catholic community.