Parts of a Cathedral – 17 Parts, Floor Plan and Section

All 17 parts on the diagram

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Start here: 9 main parts 9

Nave The long central space where the congregation gathers. It runs from the entrance to the crossing.
Aisle The side passages running along the nave, separated from it by piers.
Transept The arms that cross the nave, giving the plan its cross shape.
Choir The part east of the crossing where the clergy and choir sit.
Apse The rounded end of the building beyond the choir. Usually at the east.
Arcade The row of arches on piers between the nave and the aisle.
Clerestory The upper row of windows that lights the nave. It sits above the aisle roofs.
Rib vault The stone ceiling of crossing pointed arches. Its weight is carried down the ribs.
Flying buttress An arch that carries the push of the vault outward. It passes over the aisle to a buttress.

The floor plan 5

Narthex The entrance hall or porch across the west end.
Crossing Where the nave and transept meet. A tower or spire often rises above it.
Altar The table at the heart of the services, near the east end.
Ambulatory A walkway that continues the aisles round the apse.
Radiating chapel Small chapels that fan out from the ambulatory.

The nave cut across 3

Pier The massive pillars that carry the arcade and the walls above.
Triforium A narrow gallery or band of small arches above the arcade.
Buttress A massive outer pier. It takes the push of the flying buttress down to the ground.

How this list was compiled: Read 2026-09-26. (1) The History of Art, Parts of a church, https://www.thehistoryofart.org/architecture/sacred/church-parts/ : nave, aisles, narthex, transept, crossing, choir, altar, apse, ambulatory, radiating chapels, arcade, triforium, clerestory, towers and spires. (2) Wikipedia, Gothic architecture, https://en.wikipedia.org/wiki/Gothic_architecture : rib vaults, flying buttresses and buttresses, pointed arches, arcade, triforium, clerestory, nave, aisles, transept, crossing, choir, apse, ambulatory, radiating chapels. (3) Wikipedia, Cathedral floorplan, https://en.wikipedia.org/wiki/Cathedral_floorplan : nave, aisles, transept, crossing, choir or chancel, apse, ambulatory, chapels, narthex, altar, piers, buttress. (4) Smarthistory, Gothic architecture, an introduction, https://smarthistory.org/gothic-architecture-an-introduction/ : pointed arches, rib vaults, clerestory, arcade, ambulatory. Licence: own work

The drawing: Drawn for this site on 2026-10-05 by script from our own geometry: a French Gothic cathedral as a floor plan (walls, buttresses, piers and vault lines) and as the nave cut across at a pier, looking along it to the apse. Nothing traced. The arrangement and the proportions were checked by eye against the plan and the transverse section of Amiens cathedral in E. Viollet-le-Duc, Dictionnaire raisonne de l'architecture francaise, 1854-1868, public domain (Wikimedia Commons, Plan.cathedrale.Amiens.png and Coupe.cathedrale.Amiens.png). Not to scale and not any one cathedral. Licence: own work

How it works

These are the parts of a cathedral on a Gothic plan, the cross shape most cathedrals and many large churches share, then the nave cut across to show how its walls stand. Start with the 9 main parts.

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The floor plan

You enter through the narthex into the nave, flanked by aisles. The transept crosses it at the crossing, making the cross. Beyond lie the choir, the altar and the rounded apse, with the ambulatory and its radiating chapels curving round it.

The walls

Piers carry the arcade that opens into the aisles. Above run the triforium and the tall clerestory windows, under a rib vault. Flying buttresses carry the vault's push out over the aisle roofs to buttresses on the ground.

The high altar stands at the east end. Plans are usually drawn with that end to the right; this one is turned upright, east at the top.

Questions and answers

What is the main part of a cathedral called?

The nave: the long central hall from the entrance to the crossing, where the congregation stands or sits. Aisles run along each side of it.

What is the difference between the nave and the transept?

The nave runs the length of the building from the entrance. The transept crosses it near the far end, giving the plan its cross shape; the two meet at the crossing.

Why do Gothic cathedrals have flying buttresses?

A stone vault pushes outward on the walls. Flying buttresses carry that push over the aisle roofs to heavy buttresses, so the high walls can be thin and filled with windows.