The floor plan of the Chiesa Nuova with the monastery complex and the Oratory and an aerial photograph of the church and the Oratory. After the decision to build the Chiesa Nuova had been made, the idea emerged to build an Oratory. It proved impossible to obtain a plot to the east of the church, but if the pope expropriated the adjacent plot to the west there would be room for an Oratory near the monastery complex. The architects Arconio and Maruscelli had already done a lot of work on the project. When Borromini was commissioned to build the Oratory in 1637 the lay out of the floor plan had for the most part already been decided. Such as the small inner courtyard in the south and the big one (number 12) in the north with the sacristy in between. The long corridor was already there too. It led to the big inner courtyard and the church.
The problem that Borromini wrestled with was that the building line of the church and the Oratory were not aligned. First he wanted to put the Oratory in the middle. This idea had major disadvantages as he would have had to make Oratory smaller, which would have left no room for the door between the church and the Oratory. Borromini eventually returned to Maruscelli’s arrangement. Borromini did put a second door in the façade close to the Oratory (left).
The final decision to build a library above the Oratory was made in 1638. This decision had major consequences. The symmetry of the facade was adversely affected. And an extra bay had to be built to support the library. Finally, another floor was added. All of this meant that the facade was no longer in balance. The cross-section of the Oratory (top of the library and on the left the extra bay that served as a buttress). After the decision to expand the library Borromini was forced to make new designs for the facade.
Borromini admitted that his facade was not perfect, but there was no other solution because of the section that was already there and the fact that the facade’s axis in relation to the convent had to be maintained.
When you are close to the façade, you will discover that with the exception of the pilasters and the pediments no natural stone was used, but very subtle brickwork instead. Hardly any mortar was used and the bricks are very flat and uniform. Borromini said he was inspired by the old brickwork that you will find at the Porta Maggiore in Rome. The friars insisted that Borromini use ordinary bricks to ensure that the marble facade of the adjacent church would stay more prominent. The same applied to the decorations on the facade. The upper part of the facade is quite plain. Only the pediments above the windows are made of travertine. Extensive decorations are only found in the mid-section of the facade.
Because it was only decided mid-construction to add a library above the Oratory, Borromini ran into issues with the construction. He had to place additional pilasters on top of the existing ones. The four corners were cut, just like in the sacristy of the San Carlino. The walls are articulated by Ionic pilasters that continue right up to the cornice. The vault is relatively low. The joists running across the celling are reminiscent of gothic joists, with the one difference that these are flat. As opposed to Gothicism, the ribs serve no load-bearing function. The galleries are for musicians and esteemed visitors. Borromini used the shape of the balusters for the first time in the San Carlino. The 16th century baluster was derived from the round shape of a vase that was usually thickest just below the middle, which made it difficult to look through the balustrade. This shape also gave a static impression. Borromini no longer based his balusters on a circle, but on a triangle, that was given a concave or convex shape. In addition, Borromini mixes things up: in alternating fashion the balusters are placed at the bottom and then at the top. The result is that the balusters not only appear more dynamic, but they allow the spectator to look through more easily.
We’ll walk to the southern small inner courtyard and take a look at a column at the corner of the stairwell. The original four columns were a little too short. To save expense, Borromini raised the plinth by adding lotus leaves, which makes the column look like the sturdy stem of some plant. This neat trick was already recommended by architects in classical times.
We cross the Corso Via Emanuele II and head east toward the Piazza del Gesù.