Siano is a small residential hamlet situated in the village of Castellino. The locality, also called Castello Rustico to differentiate it from Castello Nobile, an ancient residence of the Malatigni, was attested in the 16th Century.

The construction of the hamlet seems to have originated from successive additions, taking the two towers as its centre point. The first tower has holes for swifts and a monolithic mullioned window with a depiction of a flower in bas-relief. The second boasts a dovecote in sandstone, holes for swifts and on one side, an almost completely rounded arched portal and a rammed wall.

The 17th-18th Century portico connected to the tower is of great importance. The upper part displays five different arches leaning on round columns with terracotta capitals and a portal with decorative tympanum. In the perimeter walls, there is a sandstone alcove carved with plant motifs and a semi-circular bracket holding an acephalous terracotta statue.