The magnificent cathedral dominates the city's skyline and whilst its grandeur can be admired from afar, it's really worth a closer look with a visit inside and if you can, upstairs to the roof for the most spectacular views of Milan.
Building started on the Duomo in 1386, but the largest church in all of Italy (the fifth largest in the world) wouldn't be completed for a further 600 years. It's incredible to think that men laboured their entire working lives on something that wouldn't even be seen finished by their great, great, great, great, great grandchildren.
The Bishop at the time insisted the cathedral was built from Candoglia marble, a distinctive salmon pink stone, and each piece was transported to the centre of Milan via the canals after the Duke of Milan gave permission for the quarried stone to be used free of charge for the holy building. Each piece was stamped to exempt it from charges.
As we queued to get in (note for others - buy fast-track tickets in advance!) there was the most biblical of thunderstorms. The rain was coming down in sheets, running like rivers down the streets. I'm sure it was worthy of Noah's time. Funny how things change, in days gone by the cathedral would have offered shelter and sanctuary, these days they make you stand in the rain and queue for tickets. Still, it was good to see the 14th century plumbing and drainage in action!
Entrance is €2 but it's well worth purchasing a ticket for the terrace so you can enter the rooftop area. This is €8 (half price for children) to walk up the stairs, or €13 to use the elevator.
You can get a close-up view of the spires for free from across the road in the department store rooftop cafe, but photography is difficult because of the volume of people and the glass safety barriers. It's worth paying and the heady climb to the top - although don't do it with slippy shoes and after a half bottle of champagne like I did. I got the proper horrors.
Inside the building itself, you can't help but be awestruck by the magnitude of the Duomo. The towering piers, 52 in total, one for each week of the year separate the aisles. Each column is topped with statues of saints. As you enter from the front, look for the meridian which was installed in 1786 by astronomers to mark astronomical noon by a ray of sunlight that enters from the south aisle.
It's important to remember that this is still a place of worship, so visitors are expected to be respectful. Women will be asked to cover their shoulders, although they were ok with my long denim shorts. Disposable ponchos are available to purchase if you don't have someone handy to lend you their jacket. Voices should be kept low, children under control, camera flashes are not allowed and the use of mobiles is very much frowned upon. The feathered capped guards may look like something from a William Tell story, but they mean business.
Back inside the Duomo, there are countless stained glass windows to admire ranging in date from 1473 to 1988. The intricacies, the minute details in the carving, the tiled flooring, the magnificent gilded organ pipes - it was almost too much for my eyes.
The peculiar statue of St Bartholomew, who was martyred by being flayed and crucified reminded me of those vintage anatomical drawings, all sinews and muscles.
In the vault above the choir is the Holy Nail of The Cross, a red light marking the place where a nail reputedly from Jesus' crucifixion has been kept since 1461. It is displayed to visitors every 14 Spetember when the bishop is raised up on hidden pulleys to the niche where it is hidden.
To enter the staircase for the rooftop, you need to exit the building and walk around the side, so if you want to break up your visit with lunch (or to wait for it to stop raining in our case) then you can.
The climb wasn't so bad - I forgot to count how many steps there were on the spiral staircase, but it was so worth it for the incredible views of the city. From here you can see up close the painstaking restoration work which is ongoing, replacing sections of the marble which have been eroded by time, weather, pollution and pigeon droppings.
See the buttresses and gargoyles from above, and take in the panoramic vistas which on a clear day allow you to see the mountains in the distance.
Even for a non-religious person like me, this was a visit I'll always remember.
Read my review of the hotel we stayed in during our visit to Milan, the Milano Scala Eco Hotel.