Diano Castello (Ligurian: Dian Castello[3]) is a comune (municipality) in the Province of Imperia in the Italian region Liguria, located about 90 kilometres (56 mi) southwest of Genoa and about 5 kilometres (3 mi) northeast of Imperia.

The hills surrounding the village are covered with olive groves and with vineyards that produce Vermentino, a white wine.

[5] As the name of the municipality suggests, it was originally built in the 10th century as a fortification (Castrum Diani) against incursions by the Saracen pirates.

As with many villages around Savona, it later became a fief of the Clavesana marquisate, who built a fortress and ruled till the second half of the 12th century.

In the 14th century, Diano Castello became a free municipality (Communitas Diani), that controlled the surrounding villages.