Sant’Ivo alla Sapienza is a church in Rome dedicated to St. Ivo Hélory, located in the district of Sant’Eustachio, built in the second half of the seventeenth century by the Italian architect Francesco Borromini. The church stands inside the courtyard of the Palazzo della Sapienza, seat of the ancient University of Rome, originally born, by the will of Pope Leo X, as a university chapel dedicated to Saints Leo Pope and Fortunato Martyr. The building does not seem to have a real façade, since its elevation (designed by Borromini himself) corresponds to the large exedra conceived by Della Porta and continues the dominant and uninterrupted motif of the consecutive arches. The plan of Sant’Ivo is central but with a complex geometry, because it is obtained by interpenetrating two triangles, so as to obtain a six-pointed star motif, which includes a regular hexagon in the middle. The points of the base star are treated differently: three are transformed into concave semicircular niches, the others are mixtilinear, with convexities broken up by small niches. The choice of the triangle is of a symbolic nature, in that it refers to the Trinity. The number 3 is recurrent elsewhere: the stars of the dome are 111 (1 + 1 + 1 = 3). Another symbolic number used is 12, obtained by multiplying 3 with 4, the symbol of the world and space (four are the natural elements and the cardinal points). Twelve are in fact the steps above the drum. The stars that decorate the dome are distributed on 8 levels and alternate 8 and 6 points: eight is the number of cosmic balance, six, the biblical number par excellence, is the mediator between the beginning of everything and creation (God created the world in six days).To compensate for these bold design choices, Borromini created an extraordinarily continuous and homogeneous interior, punctuated by a sequence of giant fluted pillars that highlight the six corners of the hexagon. The trabeation reproduces the profile of the plan, easily legible in its form. The effect produced by the light that enters through the dome’s lantern and the windows is highly suggestive, reflecting on the white walls and communicating a sense of intense spirituality. Unlike traditional domes, the dome of Sant’Ivo seems to undergo a constant process of expansion and contraction, with an extraordinarily bold "pulsating" effect. The dome is in fact set directly on the mixtilinear profile of the walls, almost as if the entire church had been conceived as a drum for its roof. The basic invention of Sant’Ivo is precisely the vertical continuity of the plan that develops without interruption up to the dome.
