I love taking photos of things other people don't usually pay much attention to. Architectural details fascinate me, no matter where they are. As strange as it may sound, I love visiting cemetaries, reading tombstones, and taking photos.
The photos of the vault doors in this post were taken at Cimetière du Père-Lachaise in the 20th arrondisment of Paris, and cemetaries in Nice and Collioure. Pere Lachaise is really one of the loveliest, quietest places in the city. It's hard to believe that you are in the middle of Paris as the main sound you hear is wind rustling through the trees.
While you're there, be sure to find Jim Morrison's grave--it'll be the only one with a guard keeping watch over visitors. You can buy a map just outside the gates (you'll need one), because there are so many famous people buried there. My favorites are Chopin, who is buried in a beautiful white vault, and Edith Piaf, whom you will need to look for under her family name, Gassion.
You'll be amazed at some of the vaults in the cemetary. They are the size of small homes. There are graves there from the 1700s of families that have apparently completely died off and the vaults are disintegrating from neglect, but amazingly, it's still a working cemetary. It's really impossible to see the whole of the cemetary in one day and if you do go, you need to wear sensible shoes as the sidewalks among the graves have been disturbed by tree roots from all the beautiful trees that provide the shade on a hot day.