Gaggio Montano is a comune located in the Metropolitan City of Bologna within the Emilia-Romagna region of Italy. It is situated in the Bolognese Apennines, approximately 45 kilometres south-west of the city of Bologna.
The historical centre of the town developed around the Sasso di Rocca, which is an ophiolitic rock outcrop that overlooks the Silla and Reno valleys. The most notable landmark in the municipality is the Lighthouse of the Fallen of the Mountains, a war memorial constructed on the summit of the rock in 1952.