Torre del lebbroso, Medieval tower in Aosta, Italy.

The Torre del Lebbroso is a medieval tower standing on the western side of Aosta's ancient Roman walls, featuring a square structure with external stairs climbing its outer face. Today the building functions as an exhibition space for visitors to explore.

The tower was built on the remains of a Roman tower; a square medieval tower was added in the 15th century. It was first known as Tour Friour, from the De Friour family documented in 1191, who also held the now-vanished Porta Decumana. After being abandoned and locally called Tour de la frayeur, it was bought by the Ordre de Saint-Maurice in 1773 and restored in 1890 under Alfredo d'Andrade.

The tower's name comes from Pierre-Bernard Guasco, a leper from Oneglia confined there with his sister from 1773 to 1803. His story inspired Xavier de Maistre's dialogue Le Lépreux de la cité d'Aoste, published in 1811. The building now belongs to the Autonomous Region of Aosta Valley and serves as an exhibition venue.

The tower stands at the corner of via Jean-Boniface Festaz and via Jean-Joconde Stévenin, on the western side of the Roman walls, within walking distance of Aosta's centre. Access to the upper floors is by the spiral staircase inside the 15th-century square tower, reached originally by an external covered stair.

The tower incorporates sections of an earlier Roman fortification, with original Roman windows still bringing natural light to its interior levels. These architectural layers reveal how the city was repeatedly rebuilt over many centuries.