I See London, I See France…I See Langdon's Underpants?
The characters in Dan Brown novels definitely get around. (We're talking about geographically. Get your mind out of the gutter.)
So even though our story starts in the heart of Paris, Langdon and Sophie go to a Chateau in Condécort (France), then over to London via private plane, and then up to Rosslyn, which is just outside of Edinburgh, Scotland.
They basically take an awesome European vacation—they see all the great sights, but then never get to actually relax and enjoy them. (To be fair, their trip is a little more stressful than, say, having to go to three museums in one day.)
And these locations weren't picked willy-nilly. They're all the sites of some pretty significant cultural edifices: the Louvre, Chateau Villette, Temple Church, Westminster Abbey, and Rosslyn Chapel are all testaments to the amazing things humans can create when they're at their best.
But, because you might be having a hard time picturing the most important setting, (you know: where the Holy Grail is hidden) we thought we'd help you out. At the end of the book, Langdon wakes up with the realization that he finally knows where Saunière hid the Holy Grail. His clue reads: "The Holy Grail 'neath ancient Roslin waits / Adorned in masters' loving art, She lies. / The blade and chalice guarding O'er Her gates, / She rests at last beneath the starry skies."
Langdon figures out that the old curator had hidden the Holy Grail right under the place where he could look after it on a daily basis: the Louvre.
So, the "Roslin" he's referring to is the Rose Line, which runs right through the museum. And "Adorned in masters' loving art"? refers to the insane art collection housed at the Louvre. The "blade and chalice" he's referring to reside right in the museum's entryway, and they're pretty hard to miss: And because they're made out of glass, the "starry skies" are easily visible from below. Pretty neat, huh?