The Royal Chapel of King Louis XIV. Enormous is scope, the entire complex is one of the most impressive I have ever seen. Multiple palaces (for the mistresses of the King mainly) and grounds complete with their own Venetian style canals and an Orangerie. The Sun King was perhaps nearly revered as a god among men, and requisite with this theme is a lack of Christian symbology anywhere in the multiple palaces, with the notable exception of the Royal Chapel.
Sainte-Chappelle, Paris - The most beautiful building I've ever seen...and we just stumbled upon it. If you go to Paris, make sure you don't miss it. (You have to go upstairs to see this part of the chapel. We almost left and missed it because we didn't know there was more.)