Chiesa Nuova is a churchin Rome, built for St Philip Neri
, dedicated to Pope St Gregory the Great
and Our Lady. It is the principal church of the Oratorians founded by St Philip Neri in 1561
For reference, a plan of the church is available here
The church stand on the site of a small natural depression in the plain of Campo Marzio, considered by the Romans one of the gates of hell and place of worship of the god of hell. The site was known as Tarentum, and a wide-mouthed cave there was said to be an entrance to hell.
The first church on the site was built by Pope St Gregory the Great in the late 6th centruy, and later dedicated to him. By the 12th century, its name had changed to Santa Maria in Vallicelli (Our Lady in the Little Valley) because it had stood in the valley of a small stream flowing into the Tarentum marshes.
In 1551, St Philip Neri founded the "Congregation of the Oratory", which was then recognized by Pope Gregory XIII
in 1575. Neri lived next to the church and was in charge of it. The old dilapidated church stood in a depression in the ground, where bogs and ponds formed. A new church was needed, and St Philip Neri, with the help of Pope Gregory XIII, had it built and dedicated to both St Gregory and the Blessed Virgin. Construction started in 1575, led by Giovanni Matteo da Città di Castello, then by Giacomo della Porta
. In 1577 the worked passed to Martino Longhi the Elder
, trusted architect of the largest funder of the work, Cardinal Pier Donato Cesi
. The church was consecrated in 1599.