The castle of San Floriano del Collio belonged to Patriarchate since the 11th century.
Later, it became a feud of the Ungrispachs’ family and, since 1520, it has been a property of the Formentini Vinciguerra’s, ancient noble family of Cividale del Friuli, which is still the owner.
The castle was part of the defensive system that included also Gorizia and Gradisca fortresses. It was involved in the 17th century in the cruel battles of Gradisca, fought between Venice and the Austro-Hungarian Empire.
In the 18th century, the castle lost its strategic military rule, so in 1860 it was transformed into a residence by Baron Joseph Formentini.
About the old castle, nowadays, are visible only some parts of the walls, the northern entrance and two cylindrical towers.