Exterior view

The church was Borromini's first independent commission. It was built as part of a complex of monastic buildings on the Quirinal Hill for the Spanish Trinitarians, an order dedicated to the freeing of Christian slaves. He received the commission in 1634, under the patronage of Cardinal Francesco Barberini, whose palace was across the road. Although the idea for the serpentine façade must have been conceived probably in the mid-1630s, it was only constructed towards the end of Borromini's life and the upper part was not completed until after the architect's death.

The concave-convex façade of San Carlo undulates in a non-classic way. Tall Corinthian columns stand on plinths and bear the main entablatures; these define the main framework of two storeys and the tripartite bay division. Above the main entrance, cherubim herms frame the central figure of Saint Charles Borromeo by Antonio Raggi and to either side are statues of St John of Matha and St Felix of Valois, the founders of the Trinitarian Order.

The picture shows the façade.

View the <a href="#" onClick="w=window.open ('/support/plans/b/borromin/quattro2.html', 'newWin', 'scrollbars=yes,status=no,dependent=yes,screenX=0,screenY=0,width=400,height=600');w.opener=this;w.focus();return false">ground plan</a> of San Carlo alle Quattro Fontane, Rome.