How the Duomo is built

The stone came first

In Lombardy a great church meant brick. Gian Galeazzo Visconti decided otherwise and chose marble from Candoglia, in the municipality of Mergozzo in Piedmont, and on 24 October 1387 he ceded the quarry to the Veneranda Fabbrica. That decision also set up a long supply line. Blocks travelled by water, down the Toce, across Lake Maggiore, along the Ticino and the Naviglio Grande to the docks at Sant'Eustorgio. Marble was still arriving this way until 1920.

Why the spires stand in ranks

Gothic buildings push outwards as well as down. The load of the vaults goes into tall piers and from there out to buttresses, and a heavy pinnacle on top of a buttress helps to hold it in place. The spires along the Duomo's roofline follow that logic, and on two levels you can walk among them, which shows you more of how the building works than the nave does.

The count on the outside

Gargoyles are the working part of the decoration: they throw rainwater clear of the walls. Giants and corbels are easier to read from under the walls than from the middle of the square.

Why the façade looks like two buildings

The lower portals and windows belong to a later classical taste, while Gothic spires and tracery run above. Napoleon gave the final push: the official history dates the works that completed it to 1807–1813.

Read it from the bottom up.

1. The doors, dating from between 1909 and 1965, are the newest large element.
2. The inscription Mariae Nascenti gives the dedication to Mary at her birth.
3. The top, where the Gothic outline finally meets the Main Spire behind it, seen best from a distance.

If you want to know what the words duomo and cathedral mean, see what a duomo is.

The tiburium and the Main Spire

Over the crossing rises the tiburium, the structure around the dome, and on top of it the Main Spire, built in 1765–1770 under Francesco Croce to carry the Madonnina. Together they make the skyline you recognise from a distance.

A building under permanent repair

The Fabbrica has been at work since 1387. Restoration of the tiburium and dome began in 2016, and recent work has covered the North Capocroce, the end of the north transept. The Adopt a Spire campaign, launched in 2012, is the public side of that bill. For you, it means some part of the exterior may carry scaffolding, and no official page says which part at a given moment.

One thing to try

From the south side of the cathedral, look up the wall and count the layers: wall, window, buttress, pinnacle, statue. Then go up on the roof and see the same layers from behind. The dated history covers who did what, and when.