"All descriptions of [...] architecture [...] in this novel are accurate" - Dan Brown, The Da Vinci Code
Let's put that to the test, shall we?
At the start of Chapter 10 (p. 79), we're treated to a brief description of the Saint-Sulpice church in Paris. For context, the church the text refers to is this one:
(images taken from this Wikipedia page)
Dan Brown describes this church as follows (and bear in mind I've removed nothing from his description):
Lit from beneath by banks of floodlights, the church's two bell towers rose like stalwart sentinels above the building's long body. On either flank, a shadowy row of sleek buttresses jutted out like the ribs of a beautiful beast.
A buttress is a feature retained from Gothic architecture here (this church was built halfway through the 17th century, so Gothic architecture predates this building). You might be thinking of something like a flying buttress if you think of them, as many of the great cathedrals in Europe have these.
As an example, I'll share a couple of images from my own collection.
These are Chartres Cathedral & Regensburg Cathedral. The ones in Regensburg are more elaborate and even include a small tower on top of the buttress, which yes, does help with the standard function of a buttress. (You can even spot a few flying buttresses behind the one I've circled.)
They're architectural features that have been embellished, essentially. The reason for their existence is to buttress the forces that carry the wall, which because of weight push outward. The buttresses prevent the walls from tearing and falling down.
We'll look at another image of Saint-Sulpice, and this time I'll help you identify the buttresses there.
What did Dan Brown say about them again? On either flank, a shadowy row of sleek buttresses jutted out like the ribs of a beautiful beast.
How do these in any way remind anyone of a beast? Besides, the word 'sleek' refers exclusively to the top portion of each buttress, because as you can see they end into something with an edge at the bottom.
[T]he church's two bell towers rose like stalwart sentinels above the building's long body.
We have a specific word for these towers (westworks), but I'll let that one slide. What I cannot let slide is the implication that the church has a particularly long façade (you'll note that Brown avoids using the word façade for the front of the church when he's clearly talking about that portion). It's broader than certain medieval examples, sure, but not necessarily when compared to other 17th century churches.
I decided to be fair and honed in on similar structures in Paris, since this was essentially what I did in year 2 of art history, when we specifically compared the Panthéon to other churches in Paris too (the Panthéon never ended up being used as a church due to the French Revolution and its Napoléonic aftermath, but it was originally designed as such).
What I found was the Val-de-Grâce. It began construction in 1645, while work on the Saint-Sulpice started a year later in 1646.
Note how its façade protrudes. This could clue you in to the fact that the outer sections were added later, but that shouldn't even matter in this case. It is a simple fact that this church is a lot longer than the one Brown described as having a 'long body'. Because of the Saint-Sulpice's height, the rectangular front appears almost square, and personally, as a student of art history who is somewhat familiar with this architectural period, the thing that stood out to me most was the façade's height, and not its length.
I suspect this is due to the fact that this period in history became ever more centred on Roman and Greek architecture, thanks in part to the increasing popularity and new discoveries of Classical architecture. Not all features disappeared (you can see columns being popular throughout every single architectural period in the vaguely identifiable "West", but let's say Western Europe to make this a bit clearer, although effectively each country the Romans so much as touched use features of theirs, so that includes places like Turkey and Lebanon).
Although we can't necessarily say that Brown's descriptions of architecture are wrong as such, it is rather clear to me that he's woefully overestimating his own ability to convey what architecture looks like and why something supposedly looks so special.
As it stands, I would have described a car scene with a character who's extremely religious and sees this church as follows (and I'll make it as similar to Brown's description as I can):
Lit from beneath by floodlights, the church's westworks rose above the building's façade. It was too Roman for Silas's liking – he never cared much for the pagan tastes of the modernisers. On the north and south sides, though it was hard to see in the dark, he knew buttresses in an experimental style that would put Michelangelo's Mannerism to shame interrupted the Roman work to make a mockery of spiritual Catholicism a mere century before the French Revolution destroyed it all.
(original below for comparison so you don't have to scroll back up)
Lit from beneath by banks of floodlights, the church's two bell towers rose like stalwart sentinels above the building's long body. On either flank, a shadowy row of sleek buttresses jutted out like the ribs of a beautiful beast.
I decided to shove a bit of characterisation in there, with the added anger I know traditional Catholics constantly express against modernism. Granted, they are often too clueless to identify the first vibrations of what they hate so much, as they absolutely love Renaissance work and its aftermath, but the fact remains that things like the Mannerism of Michelangelo laid the foundation for ever less religious architecture in the construction of religious buildings.
But it's not as if Brown can let Silas express any real tradcath thoughts here – his whole point with this section is to call the people Silas needs to take the keystone from heathens who've used a house of God to conceal it. It's not like you can point out that the architecture of said house of the Lord is actually a lot more reminiscent of pagan architecture than earlier examples, but I think it could've added an interesting angle (not to mention a tangible knowledge of architecture and Catholicism on the part of the author, which as you know is not something I think he has).
The experimental architects did a lot of interesting things, but in the end they designed buildings that became further removed from medieval spirituality, which is exactly why people in the 19th century started bringing back Gothic elements and why Romanticism became associated with the religious, and its opposite Neoclassicism was more associated with values we see now as the foundations of liberalism (reason, logic, civic duty, etc.). Mysticism dies in the hands of Neoclassical features, whereas a sort of secularism seems to thrive in it.
But that is basically a topic for a whole thesis, so I'll leave it at this. Thanks for spending your time to be an art history nerd with me today.
Important note: I call the features Neoclassical, as you can clearly see A LOT of classical influences here, but the actual style in this case is Baroque. As one of my professors says, you can tell apart Baroque architecture from Mannerism, because it is absolutely impossible to take a picture of Baroque architecture. I was struggling a lot with the images Wikipedia provided, simply because I can't show you the angles properly. It's only the façade that's clear; the rest would require an in-person view to properly convey.
Baroque architecture directly developed out of Mannerism.