The first architects—or ingegneri—were Filippo da Ancona and Giovanni da Milano. The latter was succeeded by Jacopo da Cortona in 1451. A year later the building was far enough advanced for the Castellan, Foschino degli Attendoli, to take possession. The day of his installation was of mystical import for the Duke, who chose a day approved by his astrologers, when the moon was waxing. Francesco, who desired to make his building beautiful as well as strong, engaged the Florentine architect Filarete to design and adorn a lofty entrance tower in the walls facing citywards. This tower, destroyed long ago by accident and time, is now represented by the modern Torre d’Umberto, in which it must be supposed that the architect has somewhat freely interpreted the scanty evidence in contemporary documents and drawings of the appearance of the original.[[25]]

[25]. A fifteenth century graphite drawing of Milan on a wall of the old monastery of Chiaravalle, a short distance from the city, shows the form of the castle at that time.

The usual quarrels arose between Filarete and his Lombard fellow-architects, whom the Tuscan scorned as mere masons. Their jealousy and impatience defeated his ideas, and he was finally compelled to abandon the work entirely to them. The Duke’s decorative projects indeed came to little. His order to Jacopo da Cortona to make windows, of such beauty of style and form as a work like this demands, in the outer façade was never fulfilled, perhaps because of the inconvenience of such openings in a defensive curtain, and it was left to the restorer in these peaceful days to insert the Gothic windows—elaborately ornamented in imitation of some of the old ones still remaining in other parts of the building—which now adorn the front.

After the first the work proceeded slowly, hindered by the quarrels of the architects, the irregularity of payments, and the dishonesty of those in charge. In 1454 the Duke’s military engineer, Bartolommeo Gadio of Cremona, was appointed to the chief post, which he held to the satisfaction of three successive despots till his death in 1484. Duke Francesco was destined never to inhabit himself this building which he had watched with such ceaseless interest, but when he died in 1466 it was complete in all its main features. Within the great walls which flanked Filarete’s tower and were guarded at the angles by two massive round towers lay the vast outer court, with fortified side gates, as well as the main entrance in the central tower. At the other end of this piazza rose a second mighty curtain of masonry, behind which lay the citadel, containing the Corte Ducale on the north side, and on the south a strongly defended inner enclosure, the Rochetta or innermost keep, the place of retreat in extremity. In this form we see the Castle to-day, though with all the defensive apparel which frowned from gates and tower and walls gone.

On the accession of Galeazzo to the dukedom, the Corte Ducale was completed with the utmost haste for his reception, and having settled himself there, the young tyrant gave rein to his extravagant passion for gorgeous decoration. While keeping architects and builders still continually at work on his new palace, he called painters from all parts of his state to fresco its walls, himself supplying the subjects. There is little doubt that everything possible to mortals was done to please a prince whose imperious will was supported by the torture chamber and the executioner, and that the palace was soon gay with the colour which he loved. Within its sumptuous halls Galeazzo entertained his guests with lavish splendour. Here Cardinal Pietro Riario was accorded pontifical state on his visit in 1473, and lay in a chamber so superbly adorned that no one had ever seen another so magnificent and princely, and here he and his host built up fantastic political schemes, which were to make the one monarch of Peter’s throne and the other king of all Italy—schemes drowned but a few days later in a poisoned cup offered to the mad young priest at a Venetian banquet.

The Duke continued the construction of the Rocchetta also, which his father had left unfinished, and gave orders for the decoration of the great Sala della Palla on its north-east side. But it is with the Corte Ducale that the fateful memories of this prince are especially associated. Thither he returned on the Feast of St. Thomas, 1476, with the glory of a victorious campaign freshly investing him, yet abstracted and pensive, possessed with a sense of the nearness of death, so that he bid the singers of his chapel to repeat every day in the midst of the joyful celebrations of the season, the mournful cry from the Office of the Dead, Maria Mater Gratiæ, Mater Misericordiæ.... In the painted halls behind the chapel the usual Christmas ceremonies were carried out, and in the Sala dei Fazoli the Yule log was solemnly lighted upon the hearth in the presence of the tyrant and his family, and of all the great feudatories of state. In the Sala delle Columbine—painted with doves—the Duke, clad in a long crimson robe, entertained his courtiers on Christmas Day, and discoursed on the greatness of Casa Sforza, pointing out with unconscious irony how firmly its fortunes were assured in the many descendants of his father Francesco then existing in health and prosperity. We may picture his tall figure on the following day, clad in the doublet of crimson satin lined with sable, for which, with characteristic vanity, he had cast aside his cuirass, fearing to appear too stout if he wore the armour beneath; and in the long hose, one crimson, one white, worn by the princes of Milan, passing through the loggia, which still exists, though much restored, and down the great staircase into the courtyard, on his way to attend Mass in S. Stefano. He had kissed his little sons, and parted from them with a strange hesitation—this man who, as his daughter Caterina proudly declared, never knew fear. Mounting his horse in the outer court, he rode out beneath the Tower of Filarete, followed by a gorgeous throng of courtiers, and his brilliant figure disappears from the Castello for ever. Later on the same day a messenger passed out of the gate charged by Bona with three rings, a turquoise, a ruby, and a precious seal, and with a vest of white cloth of gold, for the adornment of his body, which lay laced with twenty-three dagger wounds, in the Canonica of S. Stefano.

With the death of Galeazzo, the historic interest of the Castello shifts to the Rocchetta. This inner keep has remained more in its old state than the Corte Ducale, and is the most picturesque part of the castle to-day. The cortile is one of those characteristic colonnaded buildings which are generally described as Bramantesque in Milan. Two of the sides of the quadrangle, however—to the left of and facing the entrance from the outer court—are of older date, having been built by Francesco and Galeazzo Maria respectively. The columns and capitals show the character of the early Renaissance in Milan; upon the capitals are carved the shields and various devices of the dukes. The other part was not finished till later. The lofty tower at the north-east angle, called the Torre di Bona, was built during the brief regency of Galeazzo’s widow, when Cecco Simonetta hastened to complete the defences of the Rocchetta in order to ensure her authority. This measure, however, only served for her undoing at the hands of Lodovico il Moro, who, having taken advantage of her weakness and folly to possess himself of the Rocchetta, the person of the little Duke, and, in consequence, of the supreme government of the state, made his abode in this, the heart and key of the whole stronghold.

During the first years of his rule Lodovico did little to the Castle beyond completing its defences. But as time went on he allowed himself to assume the splendour of a reigning prince, and to satisfy an artistic appetite as eager as Galeazzo’s and ordered by a finer discrimination. The great artists whom he called to his court were set to work to make the palace such a home of art and beauty as the world has rarely seen. Their services were required not only for lasting work, but to design the ephemeral decorations of the gorgeous state ceremonies in which the regent delighted to display the wealth at his command. The magnificent decorations for the coming of the young Duke’s bride, Isabella of Aragon, in 1489, were designed, it is said, by Leonardo da Vinci. The regent’s own approaching marriage with Beatrice d’Este caused a great ferment of artistic activity during the next year in the Rocchetta in preparation for her habitation there. With despotic impatience Lodovico summoned all the best “painters of histories”—depinctori de istoriade—to come to Milan within two days of his order on pain of heavy fines, and show designs for the decoration of the Sala della Palla. He himself describes the room in a letter to his brother Cardinal Ascanio. The ceiling was blue, with golden stars, in similitude of the heavens, and the walls were covered with pictures on canvas representing the exploits of Francesco Sforza, whose image on horseback beneath a triumphal arch was depicted at the upper end.

With the advent of Beatrice d’Este the Rocchetta became the scene of an incomparable gaiety. The young princess filled it with new life. Her extraordinary capacity for enjoyment never knew satiety, not even in the lengthiest of state functions, which she enlivened by teasing the hoary ambassadors who occupied the place of honour beside her. In the beautiful rooms prepared for her in the south-west side of the court she lived her brief enchanted existence in the midst of the most exquisite environment which her husband’s wealth and devotion and the fine art of the Renaissance could create for her.