Built in the 16th C. by the architect Giovanni Battista from Venice (known as Venetus), this red brick building recalls the fortifications of the past and delimits the Old Town to the South. This solid, late gothic style, semi-circular structure, crowned by a Renaissance attic floor, was built on a bridge so as to strengthen the fortifications. Restored after the war, it highlights the city's mediaeval aspect. Today, it is used as a summer exhibition gallery.