Genazzano is situated on a lonely hillside in the foothills of the Prenestine mountains. From the huge Matteotti square, at the entrance to the town, can be seen the remains of a large nymphaeum (Ninfeo), a Bramante-style Renaissance construction.
The sanctuary of the Madonna del Buonconsiglio, originally built in the 13th cent., modified during the first half of the 17th, and restored during the second half of the 19th, has a neo-Classical facade with a 15th cent. doorway. Inside, is a 15th cent. Gothic-Renaissance-style canopy supported by columns.
The Gothic Cam Apolloni is one of the most beautiful buildings in Latium; it has a low-arched main doorway, three mullioned windows on the first floor, and three single apertures on the second.
The church of San Paolo, modified in the 18th cent. and flanked by a remarkable Romanesque bell-tower, contains a baptismal font (1563), a medieval holy-water stoup supported by a small spiral column, and a Renaissance holy-water stoup.
The medieval Castello Colonna, rebuilt in the 15th cent. by Ottone Colonna, who later became Pope Martin V, was modified in Baroque style and has a spectacular courtyard with a fountain and ancient water-tank.