The Metropolitan Museum's portrait of the Pincesse de Broglie, c. 1852, by Ingres, is one that I return to over and over again. If you take a quick look at this high resolution version, you'll soon see why.
Chenonceau is one of France's most renowned chateaux (castles). Fortunately for us, the official site for the chateau is quite something. You might want to take a quick look at the introduction.
And then you'll want to make a beeline for the panoramas of each room on each floor:
These are both from the wonderful Mapping Gothic France site. That site has a set of several pages devoted to St. Martin's. Apart from the panoramas, there are a brief history and nearly 100 additional images of the interior and the exterior of the church.