Characterized by the singular triangular plan, a rare shape in Italy, the tower was built in the fourteenth century following an expansion of the walls and over time has become one of the architectural elements identifying the town, so much so that it was included in the municipal coat of arms. It is part of the first section of the walls that originates from the Rocca and reaches the ancient Porta del Castello, still today the main entrance to the historic center. At the time, the wall front continued to descend as far as Porta Aretina where there was another tower of which no trace remains.
The triangular tower is today the perfect setting for the Castle Fire, one of the most anticipated moments of the Palio delle Barche, an evocative fireworks display that recalls the siege suffered during the war between Oddi and Baglioni.