The Gothic Milan Cathedral is located in the city of the same name. Its Italian name is Duomo di Milano. It serves as the archdiocese of Milan's episcopal see. With a length of 157 meters and a capacity for 40,000 people, it is one of the biggest Catholic churches in the world. The choir windows are said to be the biggest ones in existence.

The building process started in 1386 and was finished in 1965. The Milan Cathedral was already the city's center in antiquity, according to the city's layout, which has streets spreading out from or circling it. The Romans called this area Mediolanum. On this site, the Basilica of St. Ambrose was constructed at the start of the fifth century, and another basilica was added adjacent in 836. Both structures were destroyed by fire in 1075, and the Duomo was constructed in their place.

The new project was started in the brilliant Gothic style by Archbishop Antonio da Saluzzo in 1386. Many features of the cathedral are unique to Italy and follow the French Gothic architectural history, such as the two aisles. The beginning of construction, which occurred concurrently with the bishop's cousin Gian Galeazzo Visconti taking office in Milan, was viewed as a way to appease the nobles and the working masses who had been harshly oppressed by his dictatorial predecessor Bernabé Visconti. The decision to maintain the new lord's court at Pavia rather than Milan, like his father Galeazzo II, called into question the primacy of Milan in Gian Galeazzo's eyes. This decision led to the construction of the cathedral, which was also influenced by very particular political decisions.

The archbishop's, ordinari's, and St. Stephen's Baptistery palaces were all destroyed before construction could start, and the old Santa Maria Maggiore cathedral was converted into a stone quarry. The enormous new structure quickly gained popularity among the populace, and the shrewd Gian Galeazzo and his cousin, the archbishop, were able to amass significant gifts for the advancement of the construction. The Fabbrica del Duomo, an organization with 300 personnel and headed by chief architect Simone da Orsenigo, carefully oversaw the building schedule. Marble from the Candoglia quarry was given to the Fabbrica exclusively, and Galeazzo exempted it from taxes.

Nicolas de Bonaventure, a Frenchman who was named principal architect in 1389, is credited with giving the cathedral its distinctive Gothic style. When the builders needed technical assistance to elevate the stones to an unprecedented height ten years later, they called in another Frenchman, Jean Mignot, from Paris to assess and improve the work that had already been done. Mignot declared that all previous work had been completed without knowledge and in pericolo di ruina ('risk of ruin'). Mignot's predictions were disproven in the years that followed, but they still inspired the architects of Galeazzo to further their tools and methods.

While the lord (who in 1395 had become Duke of Milan) intended to transform the cathedral into the dynastic mausoleum of the Visconti by inserting the central part of the funerary monument of the cathedral of his father Galeazzo II, this met with strong opposition from both the factory and the Milanese, who wanted to emphasize their autonomy. Relationships between Gian Galeazzo and the upper management of the factory (elected by the citizens of Milan) were, however, Gian Galeazzo was obliged to choose the Charterhouse of Pavia as the location of a new construction site that would be used only by the Visconti dynasty due to an altercation that occurred.

By the time Gian Galeazzo passed away in 1402, over half of the cathedral had been finished. The most important achievements from that time period were the graves of Marco Carelli and Pope Martin V (1424) and the windows of the apse. However, progress stalled until 1480 due to a lack of funds and ideas (around 1470). The paintings of St. Eligius and St. John Damascene, both by Niccol da Varallo, as well as St. John the Evangelist, by Cristoforo de' Mottis, are still standing. The nave and aisles were finished in 1452, under Francesco Sforza's reign, up to the sixth bay.

When Leonardo da Vinci was working for Duke Ludovico Sforza in Milan in the late 1480s, one of the most significant moments in the cathedral's history occurred. The famous Renaissance artist participated in discussions and disagreements on the progress of the construction and designed a number of solutions for the dome that were never implemented. Some of his ideas, including the double-hulled dome solution that would balance stresses in the fragile structure of the building, are depicted in several drawings by him that have survived. In 1499, Leonardo left Milan.

Under Ludovico Sforza, the octagonal dome was finished between 1500 and 1510, and the interior was embellished with four series of fifteen sculptures each, depicting saints, prophets, sibyls, and other figures from the Old Testament. Except for the Guglietto dell'Amadeo, a dome with a tall spire atop the transept and constructed by Giovanni Antonio Amadeo between 1507 and 1510, the exterior remained mostly unadorned. Despite being a Renaissance masterwork, it blends very nicely with the church's overall Gothic design.

The magnificent Trivulzio candelabrum from the 13th century and St. Bartholomew by Marco d'Agrate were installed here in 1562.

The Milan Cathedral is a sizable church with five naves, a central nave, four aisles, and at least forty pillars. A transept connects the naves, and the choir and apse are located on either side. Only the unfinished central nave of Beauvais Cathedral, which is 48 meters high, is taller in a comparable structure than the center nave of this one, which is 45 meters high. The hall-space tendency is explained by the way the aisles are spaced unevenly and closely follow one another in height. Except for the ambulatory, the interior is dark due to the small windows. Latin American Gothic architecture tended to have fewer little apertures and more substantial ones. A ornamentation of sculpted capitals breaks up the pillars at the base of the vaults. The exterior is lavishly ornamented, made of marble, and has windows with flamboyant tracery that is not native to Italy.

However, when we examine the architectural design, we can observe that it is more influenced by the oblong bays found in French and German models. A typical Italian floor layout would include nearly square bays with pillar spacing.

The interior is famous for its huge, oddly shaped, fasciculated pillars that are crowned by a sculptured canopy that contains statuary. Metal bracing have been added to strengthen the pointed arches that divide the naves. Simple ribbed vaults are embellished with intricate tracery motifs in some places.

Outside, some excellent sculptures can be seen up close thanks to the rooftops. It's amazing to see the forest of pinnacles, spires, and crests from the roofs. The Madonnina, a 1774-opened work of gilded copper art by Carlo Pellicani, stands at the church's highest point.

When we examine the architectural design, we can observe that it is more influenced by the oblong bays of the French and German models. A typical Italian floor layout would include nearly square bays with pillar spacing.