The foundation stone for Sant'Ivo was laid in January 1643, the structure was completed in 1648, and decoration begun in 1659 and the floor was finally laid in 1660. In the church of Sant'Ivo Borromini evolved a structure of the most startling originality within a space restricted by the earlier designs of Della Porta. The plan is based on two equilateral triangles which interpenetrate to form a six-pointed star (the star of David) on the outer periphery and a regular hexagon as the central space surrounded by 6 alternating angular and semicircular bays. These contain 12 niches, which were to contain statues of the 12 apostles. The decoration was not carried out until the pontificate of Alexander VII Chigi and thus contains many references to the Chigi arms, such as crowned monti and stars. Sant'Ivo is the Church of the University of Rome. / 'Sant'Ivo has a central ground plan, in the form of a hexagon of 6 triangles, contained, as it were, within a circle, with concave and convex walls. This variety of line was unified by giant pilasters and by a high cornice, given great emphasis. The pilasters continue upwards in the moulding of the dome: thus in the lower part of the cupola the plan of the church is echoed, while at the top, below the lantern, the form is circular, making the vertical thrust almost awesome. In this reduction from multiplicity to unity, from variety to the simplicity of the circle, lies much of the fascination of this church: geometrical succintness and inexhaustible imagination, technical skill and religious symbolism, have rarely found such a reconciliation.' Rudolf Wittkower, Art & Architecture in Italy, 1600-1750. See also 'Borromini' by Anthony Blunt.
Archivision Inc. (all images copyright Scott Gilchrist / Archivision.com)