Santa Maria del Rosario e San Pietro Chanel
was a 19th century convent church, now a chapel. The dedication is now jointly to the Blessed Virgin Mary under her aspect of Our Lady of the Rosary, and St Peter Chanel. The former name was Santa Maria del Rosario di Pompei.
For reference, a plan of the church is available here
The church was built to serve the Provincial Curia at Rome of the Marist Fathers, who also ran an international college which was adjacent. It was also a center of devotion to Our Lady of Pompeii, the main shrine to whom is close to the famous ruined city near Naples. The architect was Pio Piacentini, who used an original design executed by a French Marist called L. Desroziers in 1886. The result is in a monumental neo-Baroque style, and was completed in 1898.
The former convent has been restored as a "boutique guest house" principally for Australian pilgrims and visitors to Rome. The work, sponsored by Cardinal George Pell in 2011, involved the complete and meticulous restoration of the church, which has been cleaned outside and had its décor inside restored. Artworks appealing to Australian and Oceanic devotional interests have been added, and on re-consecration the dedication was changed to Our Lady of the Rosary and St Peter Chanel (the protomartyr of Oceania).