Located about 70 metres from the main gate, the 15 metre high Chiassino Tower is cylindrically shaped to the front and squared at the back. It is spread over three floors and each floor is equipped with three firing positions for handheld firearms. These positions are characterised by splayed inner walls and firing slots visible from the outside. The tower was a powerful centre of fire for the formidable series of armaments it could be supplied with. Although small, it was a key point of defence for the walls and for the gate itself. Its construction can be traced back to the reinforcement of the fortifications of Montefollonico in the year 1479, although there is no written document that attests to this. It is currently a private home.