Using Google Earth (or Google Maps, which can be easier), search for
51 Rue de Montmorency Paris France
Go to street view and click the camera icon closest to the crosshairs.
You'll find yourself in a narrow street, behind a white truck. As the view approaches this spot, you'll see a purple sign on your right that reads "Hypso".
At this point, you might need to back up and see if you can get closer to that white truck.
When you're right behind the truck, turn to your right. You'll see a stone facade on a building, with some REALLY old writing (in archaic French) carved in it. Look up at about the second story level. There you'll see two signs on the front of the building. The one on the right tells the story:
MAISON DE NICOLAS FLAMEL ET DE PERNELLE SA FEMME.
(Home of Nic(h)olas Flamel, and of Per(e)nelle, his wife.)
This is what brought a lot of the story home to me. It's less than a mile from Notre Dame, as the crow - or raven - flies; a bit further by walking - past Rue Pernelle and the necessary detour to the intersection with Rue Nicolas Flamel.
I showed this to the sixth graders at the school where I read Alchemyst/Magician/Sorceress last year; they were impressed with it, and even more so when I produced the online menu for the Auberge. I've never studied French; fortunately, one of the "real" teachers could help.
That inscription in archaic French reads: "Nous homes et femes laboureurs demourans ou porche de ceste maison qui fut faite en l'an de grâce mil quatre cens et sept somes tenus chascun en droit soy dire tous les jours une paternostre et un ave maria en priant Dieu que sa grâce face pardon aus povres pescheurs trespasses Amen".
This version of French is so old that Google Language Tools can't really do much with it. It does state that the house was built in "the year of grace one thousand four hundred and seven". The English language changes over time. So, apparently, does French!