What to See Inside the Duomo Milan

Nine named things, in the order you meet them, each with what it is, where to stand and how long it takes. Most visitors walk past four of them, and two — the red light in the apse and the line cut into the floor — mean nothing at all unless somebody tells you what they are.

Saint Bartholomew Flayed, in the south transept

What it is: a marble figure of the apostle carrying his own skin over his shoulder like a cloak, carved by Marco d'Agrate. The musculature is anatomical rather than devotional, which is the point of it and the reason it stops people.
Where: the south transept, past the crossing on your right as you walk up the nave.
How long: five minutes, and you will want them.

The Holy Nail, 45 metres up

What it is: the Holy Nail, a relic held by tradition to come from the Cross, found in Jerusalem in the fourth century by Helena, mother of Constantine, and brought to Milan. It sits in a tabernacle in the vault above the choir, marked by a small red light you can see from the floor. Once a year it comes down, on the Rite of the Nivola.
Where: look up, above and behind the high altar.
How long: two minutes, once you know where to look.

The stained glass — 55 windows, six centuries

What it is: fifty-five windows spanning from the fifteenth century to the nineteenth, the apse trio among the largest in Europe. The later ones are enamel-painted rather than pot-metal glass, which is why the palettes do not match from bay to bay.
Where: the apse windows are behind the high altar; the older glass is in the side aisles.
How long: fifteen minutes, more on a bright morning.

The Quadroni di San Carlo

What it is: a cycle of very large canvases on the life and miracles of Carlo Borromeo, hung down the nave. They are not permanent fixtures: they go up for the saint's season in the autumn and come down again.
Where: the nave piers, when they are hanging.
How long: ten minutes if you catch them.

The meridian line in the floor

What it is: a brass line set into the paving with zodiac markers along it, and a small aperture high in the south wall that throws a spot of sunlight onto it at solar noon. It was laid by astronomers to fix the calendar, and it is the least noticed working instrument in the building.
Where: the floor of the north aisle, running across your path near the west end.
How long: five minutes, ideally near midday.

The Scurolo di San Carlo

What it is: the crypt beneath the choir holding the body of Carlo Borromeo in a rock-crystal casket. It is quiet in a way the nave above it never is.
Where: down the stairs behind the high altar.
How long: ten minutes. It is a €3.50 add-on or part of the €15 Culture Pass, and it closes on Sundays and religious festivals.

The Baptistery of San Giovanni alle Fonti, under the square

What it is: an octagonal baptistery built in 378, where Ambrose baptised Augustine in 387, when Milan was the capital of the Western Roman Empire. Eight columns stood around a large octagonal font, and the font is still there. It was demolished and buried from about 1386 to make room for the cathedral, along with the footprints of Santa Tecla and Santa Maria Maggiore.
Where: down the stairs from inside the cathedral, under the parvis.
How long: thirty minutes. Included in the Culture Pass, or a €5 add-on.

San Gottardo in Corte, off the museum

What it is: the fourteenth-century ducal chapel, reached through the museum rather than from the square, and included in the same €10 ticket as the cathedral. Almost nobody who holds that ticket goes in.
Where: through the Duomo Museum in the Palazzo Reale.
How long: ten minutes. Closed on Wednesdays with the museum.

The Duomo Museum, and why your ticket already covers it

What it is: the Fabbrica's own collection of statues taken down from the facade and the roof over six centuries, its treasury, and the full-size replica of the Madonnina — the only way to see at eye level a figure that otherwise stands 108.5 m up.
Where: across the square in the Palazzo Reale, a different building from the cathedral.
How long: forty-five minutes. Closed on Wednesdays. A Duomo Milan tickets bought at the Fabbrica's counter includes it and most visitors never realise.