What is a triforium? If you’ve ever looked up inside a Gothic cathedral, you might have spotted a narrow, hidden passage running above the nave. This architectural feature, known as a triforium, is a gallery tucked between the main arcade and the clerestory. Once essential for structural support, ventilation, and even secret storage, the triforium has largely faded into obscurity. In this article, we uncover 7 surprising facts about the triforium and its place in cathedral history.
As a child, I was immensely fascinated by cathedrals. The vast space, the stained glass – impressive! But what really captured my imagination was that narrow, mysterious corridor, high up there. ‘Could you walk there?’, I wondered. ‘And who was that corridor made for?’
Now I know that this ‘corridor’ is called the ‘triforium’. A gallery that is usually hidden from visitors. It was only when I walked there myself that I understood the magic of the triforium.
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1. The triforium is a (hidden) gallery high up in the church
A triforium is a narrow gallery in a Gothic church, usually above the side aisles and below the light aisle (the row of tall windows in the nave).
You can see it as a series of arches, often ornately decorated, that add an extra layer to the architecture.
The name comes from the Latin tres (three) and foris (opening). Literally it means ‘three openings’, referring to the usual three-part layout of the arches. Only… as is often the case in medieval architecture, this rule is not always correct. Some triforia have four openings, others five.
The triforium is located exactly at that height where you just can’t see it properly, but where your imagination has plenty of room. Because say it yourself: when you look up in a cathedral and see that mysterious corridor, don’t you wonder what happens up there?
2. The triforium is older than you think
Although the triforium is often associated with Gothic cathedrals, the concept has been around for much longer. In classical antiquity, galleries in buildings were very common, and early churches adopted this principle.
- Roman basilicas – Here, second-floor galleries were a place for merchants and public discussions.
- Early Christian basilicas – Here, the triforium was often reserved for women, to give them a separate place in the church.
- Byzantine churches – Many Orthodox churches had galleries overlooking the nave, a function partly similar to the later triforium. Consider, for instance, the Hagia Sofia.
3. The triforium became essential in Romanesque architecture
In the Romanesque period (11th–12th centuries), the triforium became an integral part of church architecture. It provided additional stability to the walls and vaults by helping to distribute their weight, preventing the walls from being pushed outward.
Beneath the triforium, a gallery was often built. Unlike the enclosed triforium, galleries served a more functional role, allowing both light and air to circulate through the church, improving ventilation. In some churches, they also provided a secluded space for clergy.
Notable examples of churches with both a triforium and a gallery include the Basilica of Saint-Remi in Reims and Laon Cathedral.
4. The triforium kept the Gothic cathedral standing
With the rise of Gothic architecture, the triforium became even more important. Gothic cathedrals reached higher and higher. But without a sturdy structure, it would end disastrously.
The triforium acted as a buffer between the heavy vaults and the outer walls. It worked together with the air arches and buttresses to keep the church stable.
So without triforia, Gothic churches would have been much more unstable. Besides an important constructive function, triforiums were also increasingly used decoratively.
5. Triforia became mainly decorative over time
During the Gothic period (12th–15th centuries), triforia were often adorned with elaborate arches and carvings. However, their functional significance gradually diminished. In some cathedrals, such as Amiens (1220–1247), they remained present but took on a more decorative role.
Unlike in earlier Romanesque churches, where triforia were larger and structurally integral, those in Amiens were relatively lower in proportion to the soaring clerestory above.
Yet, instead of being backed by a solid wall, the triforium in Amiens features openings that allow additional light to filter into the church—an architectural innovation that enhanced the brightness of the interior.
Why? Gothic was all about light and height, in the vision of the famous Abbot Suger. While Romanesque churches still had small windows, Gothic architects therefore allowed huge stained-glass windows.
Around 1300, the triforium was therefore replaced in many cathedrals by greatly raised windows in the nave. But… didn’t the triforium have the function of distributing forces and keeping the cathedral from collapsing?
This was a problem that had to be tackled. Therefore, among other things, air arches and buttresses were installed on the outside. This reduced the need for the stabilising layer (the triforium).
In French cathedrals, the triforium became relatively smaller compared to the increasingly large stained-glass windows in the nave. In England, it remained a striking architectural element.
In some cathedrals, such as Lincoln and Westminster Abbey, it took on a strong decorative role. There, it was richly decorated and highly visible, but remained smaller than the pillar arches.
6. A pseudotriforium is an illusion: only arches, but no corridor
In the later Gothic period, you rarely see a triforium with a real walkway. Sometimes, in these types of churches, you see something that looks like a triforium, but where a wall appears to have been bricked in front of the aisle.
We call this a ‘pseudotriforium’ or a blind triforium: a row of arches against the wall, but without a passage. Basically just an optical illusion. Often intended to create depth and make the church even more impressive. This principle was often used in neo-Gothic in particular.
7. Can you actually walk on the triforium or not? Sometimes, if you're lucky...
Although most triforia are off limits, you can actually walk on them in a few churches. A few must-sees (my own experience):
- Domkerk Utrecht – This narrow corridor takes you all the way around the choir via the transept. A view inside the church gives a fantastic perspective! Read more about the triforium of Utrecht’s Domkerk in this article!
- Bayeux Cathedral – A guided tour takes you behind the triforium, but also for (a small part) through the triforium, with a great view into the choir and nave of this cathedral.
- Laon Cathedral – Here, on a guided tour, you can visit another early Gothic gallery (highly recommended!), where you can even still see the characteristic green tiles. These large galleries soon fell out of fashion and were ‘swallowed up’ by the pointed arches of the nave.
- Westminster Abbey (London) – The ‘Abbey Gallery’ offers a unique view of the church.
Westminster Abbey's Triforium: From Forgotten Repository to Historical Treasury
Westminster Abbey has been the scene of English coronations and royal ceremonies for almost a thousand years. But high above the nave, at a height of 21 metres, lies a hidden space that went virtually unnoticed for centuries: the triforium.
Why is this triforium special?
- Never been open to the public since the 13th century.
- Used as storage space for ancient furniture, papers and even stained-glass fragments.
- Recent archaeological research revealed a wealth of historical finds.
What was found?
- 30,000 fragments of stained-glass windows, some dating back to the 13th century.
- Invitations to the coronation of Queen Anne (1702), probably left by spectators.
- A rare 17th-century playing card and tobacco wrapper from 1685.
- Animal bones, pots, newspapers and medieval shoes-a time capsule of 700 years.
What happens next?
The abbey is transforming the triforium into a museum: the Queen’s Diamond Jubilee Galleries. A new tower will soon offer visitors access to this once hidden place. For the first time ever, the public will be able to admire Westminster Abbey from this unique, 21-metre-high vantage point.
The triforium began as an important structural and functional part of cathedrals, but its function gradually changed. Towards the end of the Middle Ages, it was increasingly replaced by taller windows, while in England the triforium was actually used as a decorative eye-catcher.
And if you ever get the chance to walk across a triforium… do it! And take a good look around, you might see some remnants of days gone by!
LUX Travel Tips
- The Cathedral Notre-Dame of Laon is a must see, and a guided tour highly recommended. Book your guided tour at the local Office de Tourisme in Laon
- I stayed in an authentique French hotel, Hotel de La Banniere de France. No fancy modern rooms, but warm and cosy and a great host. Located just a 5 minute walk from the cathedral and 5 minutes to St. Martin’s.
- If you visit Utrecht to see the Domkerk, get yourself a room in… a church! Just a stone’s throw from the station you’ll find Bunk, an old church that has now been transformed into a bar, restaurant, and hotel. Book your room here.
- If you visit Amiens, this 150 m2 luxious appartment is just opposite to the cathedral! That’s why its called ‘Coté Cathédrale‘
