Ponte degli Alidosi, Renaissance stone bridge in Castel del Rio, Italy.

Ponte degli Alidosi is a stone arch bridge over the Santerno at Castel del Rio, with a single hump-backed span of 42 metres and a rise of about 19 metres. Five rooms were built inside the structure, used by guards to collect tolls and also as cells for prisoners.

Construction began in 1499 under architect Andrea Guerrieri, commissioned by the Alidosi family, and was completed after two decades of building work. The bridge became an important crossing point and has remained a significant structure in the region.

The five rooms built inside the bridge were used by guards to collect tolls, and some also served as cells for holding prisoners. The bridge was commissioned in 1499 by Obizzo II Alidosi from the architect Andrea Guerrieri for 500 gold ducats, to show the power and stability of the Alidosi family after the loss of the lordship of Imola.

The bridge remains in good condition and is easily accessible to visitors from nearby walking paths in the area. Exploring on foot allows you to discover other historical sites and monuments in the surrounding region at a comfortable pace.

The five rooms inside the bridge were probably built for structural reasons and were used by guards to collect tolls; some also served as cells for holding prisoners. The single 42-metre arch and a rise of about 19 metres let the structure withstand the Santerno's flood surges over the centuries.