The Covolo di Butistone is an old military fortification, which once barred the Brenta Canal between Primolano and Cismon del Grappa until the end of the eighteenth century. The Covolo had been erected for the defence of one of the main communication routes between the Italian peninsula and Germany.

Today you can see the remains of the fortification in the cave, where you can clearly identify the altar of St. John the Baptist, the embattled balustrade, a well, a cistern, posts for the culverins, a prison and a room for the troops.