Torrione Farnese, Renaissance tower in Castell'Arquato, Italy.

Torrione Farnese is a 24-metre Renaissance tower with a square base, built entirely of brick, in the lower part of Castell'Arquato. Four slanted trapezoidal bastions project from its corners, each pierced by small rectangular windows, with bare walls and round arches between them. A loggia of 16 pillars and the roof crown the top; inside are five floors, and a 16th-century fireplace remains on the second.

Construction began in 1527 under Bosio II Sforza di Santa Fiora, lord of Castell'Arquato, to a design of Michelangelesque taste by an unknown architect; it stopped in 1535, reportedly on Bosio's death. Work resumed in 1545 through his son Sforza I Sforza and was completed in 1575. The tower served military purposes within the town's defences, also to spot enemy attacks.

The name Farnese comes from the family that acquired the tower in the 17th century, not from its builders: it was begun in 1527 for Bosio II Sforza di Santa Fiora and finished in 1575 under his son Sforza I Sforza. Since 2009 the tower has housed the Gens Innominabilis school of arms, where medieval combat techniques are studied and practised.

The tower stands in the lower part of Castell'Arquato and is not open as a monument: since 2009 it has housed the Gens Innominabilis fencing school, which practises medieval combat techniques. Visitors see the brick exterior, the four sloped corner bastions and the 16-pillar loggia from outside; interior floors and the spiral stair are not part of a public visit.

The tower's four corner bastions are angled trapezoids, a design probably derived from the "criterio di fiancheggiamento nell'offesa e nella difesa", the principle of flanking in attack and defence. Inside, three of the four bastions hold octagonal rooms, while the west bastion contains a small central room with a helical spiral staircase.