The first step in this transformation was the building of the Palazzo Ducale, started by Francesco I in 1634, to a design by B. Avanzini on the remains of Obizzo's castle. The palace, a fine example of XVII Century secular architecture, is elegant but massive, with its three towers emerging from two long wings of three floors each, surmounted by a marble balustrade. The central tower, featuring a rooftop loggia topped by a small tower, pillars and its lesenes, has a strong upward thrust balanced by the drier horizontal lines of the facade featuring pairs of windows. The building works dragged on for centuries, and the last statues sculpted by G. Graziosi were only added to the left-hand balustrade in 1926, replacing the worn wooden originals. (Anyone wishing to take a closure look at these statues can visit the Gipsoteca Graziosi in the Palazzo dei Musei, where the plaster models of Bacchus and Venus are on show). The keynote of the palace is dignity: large windows with copings that change from straight to curved to triangular in the succession from the ground to the second floor, pillars and pilasters, two double bands of moulding to mark the separation between the floors, curved windows in the cornice decoration, a marble balustrade surmounted by statues virtues and characters from mythology, and two imposing muscular statues (Hercules and Aemilius Lepidus) each side of the main doorway. Take a look at the Palazzo Ducale from the other end of via Farini; only the central section is visible, and it blends with the surrounding buildings imposingly but with a surprisingly light touch.

The Scuderie Ducali, or Ducal Stables, built in the XVIII Century on Corso Canalgrande right beside the palace, are less striking but still worthy of note. They are now in use as a cavalry barracks.

Since it now houses Italy's main Military Academy, the Palazzo Ducale is only open to the public on request for guided tours and on 4 November, or the Sunday nearest to that date. This is the only opportunity for taking a stroll through the main courtyard, or Cortile d'Onore, beyond the north facade of the palace, all the way to corso Vittorio Emanuele II (once the site of Modena's canal port), following a route much used by the whole city until the beginning of this century. It is also a chance to admire the sober beauty of the Cortile d'Onore, with its serliana motif giving it lightness and an austere elegance, also underlined by the marble balustrades on the ground and first floors.

On the left of the Cortile d'Onore, a side loggia leads to the Scalone d'Onore, or state staircase, which is the other architectural jewel normally concealed behind the facade of the Palazzo Ducale, and combines functionality and solid elegance with an unusual luminosity provided by the fact that it overlooks two courtyards. The interior of the Palazzo retains very little of the old ducal residence, the main traces of which are now found in the picture gallery in the Palazzo dei Musei. However, XVII paintings remain on the ceilings of the Salone d'Onore and the adjoining room, and offer interesting examples of a style which filled spaces while also creating the illusion of moving beyond them. Naturally, the focus is very much on the glorification of the Este dukes: in the Salone d'Onore, the warrior princess Bradamante is being crowned by Jove on Olympus, while the Este eagle on her shield identifies her as the progenitrix of the family and its military glories. (These frescoes by M.A. Franceschini in the Salone d'Onore have unfortunately been obscured by the smoke of an accidental fire; a better preserved example is the "San Carlo praying for the plague victims" in S. Carlo church).

During the last century, the spirit of the Risorgimento avenged itself on the Este family by placing the monument to Ciro Menotti, the leader of the uprising in 1831, who was captured and hanged by Francesco IV, right in front of the entry to their former palace. The statue of Liberty in Piazza San Domenico beside the left wing of the Palazzo Ducale reflects another change of historical fortunes; taken from its pedestal during the Fascist period, it was re-created by the local sculptor M. Quartieri and returned to its place in the early Eighties.