Church of St Charles at the Four Fountains

On Via del Quirinale, San Carlino is a small Roman Catholic church designed by Francesco Borromini. Its Baroque design rewards a close look: the façade bends between concave and convex curves, while the white interior draws attention to the architecture rather than elaborate decoration. Inside, look up at the oval dome, where crosses, hexagons and octagons form a pattern that narrows toward the centre. Hidden windows bring light into the dome, giving it a floating appearance. It is a compact stop for anyone interested in Borromini or Rome’s Baroque architecture.

Borromini’s use of curves

San Carlino’s small scale makes the design especially easy to read. The façade shifts between concave and convex curves, giving the front a sense of movement. Tall Corinthian columns stand on plinths beneath the main entablature. Behind them, smaller columns frame niches, windows and sculptures.

Borromini worked with familiar elements of classical and Renaissance architecture, including columns, capitals and coffered surfaces, but arranged them in a less rigid way. Curves carry through the building, from the façade to the interior. The design makes the church feel more spacious than its compact footprint suggests.

The dome and interior

Inside, the church is almost entirely white, with little emphasis on gold or elaborate colour. That restraint keeps attention on the lines of the architecture and the changing shapes of the walls. Concave and convex surfaces give the interior a sense of motion.

The oval dome is the main focus. Its coffers form crosses, hexagons and octagons, with the shapes becoming smaller toward the centre. Windows hidden from direct view bring light into the dome and contribute to its floating appearance. Take time to follow the pattern upward rather than viewing the ceiling at a glance.