The Oratorio del Santissimo Crocifisso
is a 17th century oratory dedicated to the Holy Cross, located in the rione Trevi. The oratory is actually a small chapel as oratories do not have altars.
For reference, a plan of the church and fresco layout is available here
The oratory was built in memory of a miracle that occurred in 1519, when the local parish church San Marcello al Corso burned down. A 15th-century wooden crucifix miraculously survived the fire. When everything else was destroyed, it was found intact after the fire with a lamp still burning before it.
When a pestilence swept through the city in 1522, the Spanish Cardinal Guillermo de Vich organized a great procession of people of all social levels, who carried the Crucifix solemnly to Saint Peter's. The plague ended, and this second prodigious event led the Cardinal and many prelates and Roman noblemen to institute the Societa del Santissimo Crocifisso di San Marcello. A Confraternity was founded as a result in 1526, called the Archconfraternity of the Most Holy Crucifix (Arciconfraternita del Santissimo Crocifisso in Urbe).
An oratory was proposed as a headquarters for this confraternity and was only finally built by Giacomo della Porta
in 1566. After the building was finished, the interior walls were given a very important fresco cycle based on the Legend of the True Cross to be found in the Golden Legend
, based on earlier sources, of Jacobus de Voragine
, and several artists worked on this for six years from 1578. In 1578,
This oratory became famous in the 17th century for its contribution to the new forms of religious music. The oratory was restored by the government in 1999, and continues to be a noted music venue.