Nick Z.
Yelp
Yeah, if you're from Europe, maybe castles are old hat. But I'm not from Europe, and castles are still just about the coolest thing to us, especially if you grew up playing with Lego castles, dressing up like knights and Robin Hood, and watching the world's greatest movie....Princess Bride...
You can imagine my excitement to learn that there was a castle just a few metro stops from the hotel. You don't get to say things like that in the US. If you're lucky enough to even be in a city WITH a metro, you'd be more likely to say, 'yeah...there's a McDonalds a few metro stops away.' But here...here there's a castle.
This place is pretty awesome -- you can wander around outside to your heart's content for free, and if you want to enter into the Sainte-Chapelle and the keep, it's 9€, money well spent in my opinion. The Sainte-Chapelle is gorgeous - it's not as enormous as Notre Dame, but it does come without the huge crowds, so you get a more intimate experience especially if you're there during the off-season.