I have sprinkled my coins on some books again. This decorative volume by Paul Koudounaris is on my bedside book stack right now and I thought you might enjoy a glimpse! I have a strong fascination towards the history of burial rites and charnel houses (working at the graveyard for many summers didn't really erase that macabre trait), and this book offers tons more information on the subject. It even has a vast list and maps of the sites around the globe, I had no idea Europe has so many!
The only ossuary I've seen with my own eyes is Sedlec Ossuary in Kutna Horà (you can find a post about it in here). Twice I've been to Paris and twice I've failed to visit the famous catacombs (although I did get a good look on Père Lachaise), maybe third time's the charm?