The main façade of the building, facing west, overlooks Piazza Dante and borders the east side of the square. An earlier construction dating back to the Mediaeval period was associated with the complex of the nearby Aldobrandeschi fortress and church dedicated to San Giorgio, both of which were abandoned and subsequently demolished in the course of time while the Palazzo became the town residence of the family Aldobrandeschi. A long period of decadence followed with the slow, inexorable deterioration of the building, leading finally to the decision to knock down and rebuild what remained of it. The new construction, situated in the heart of the historical part of the town of Grosseto, was officially inaugurated on May 31st 1903.
The building presents a polygonal plan and is developed principally on four floors, characterised by a clearly neo-Gothical style as seen in the division of the volumes and explicit use of formal and decorative elements, inside and out, and in the materials chosen such as travertine and brick, clearly inspired by the public buildings of Siena in Gothic style.
The main façade has an articulated, asymmetrical pattern and is composed of four separate nuclei, two towers and at intervals two lower constructions. The ground floor has a footing in travertine and a series of apertures – an archivolted portal, five windows and a loop-hole – with segmental arched and ogival arched lintel (the six tympani of the portal and apertures contain coats of arms with heraldic symbols).
The first floor is more symmetrical with seven three-light windows (three-leaved with marble cippi, arched lintels in brick and coats of arms in the tympani as for the portal below). The central window is actually a door-window giving onto a small balcony with marble brackets in Renaissance style and a sill in marble traforato decorated with tracery. The third floor has three two-light windows (again three-leaved with marble cippi) and one four-light window where the central tower is. This is situated on the west end and has also two square windows with marble moulded cornices. The frontispiece concludes with a corbelled cornice (with small brick arches and brackets in marble) and crenellated attic in brick and travertine in which the merlons are separated by simple loop-holes.
Inside, from the portal that gives onto the square, there is a passage with Gothic characteristics featured in the decorations on the walls and in the mock cross vault. The stone stairway of Scarpian inspiration, is instead part of the restoration work carried out in the nineties. On the right of the passage you enter a large meeting room, also recently restored and some utility rooms. On the left there is the caretaker's lodge, the back stairway and the lift. On the first floor there are the administration offices and a Council Room that has three ogival windows with one light on the north wall giving onto a small internal cloister, while the walls are decorated in neo-Gothical style by the Florentine painters Torrini and Vanni, as on the ground floor and the façade, and the wooden benches and chairs designed by the architect Lorenzo Porciatti from Grosseto are also characteristic. The third floor is reserved for offices only, arranged on either side of a central corridor, while the fourth floor is made up of one single room which is the interior of the west tower.