That’s one of the reasons I love HN, you find some posts like this that are completely out of this world!!!
Being Greek and a sci-fi fan, I need to find this book :-)
The book is hard to find. This copy is sold for 9000 CZK (380 Euro): https://www.trhknih.cz/kniha/9uwthe8b
Or you can read it in the study room of the National library (Klementinum): https://aleph.nkp.cz/F/83GIEU45K19XBDL2VVT6CJBMH2LA526L5YQ9U...
The Sedlec Ossuary is a Roman Catholic chapel, located beneath the Cemetery Church of All Saints, part of the former Sedlec Abbey in Sedlec, a suburb of Kutná Hora in the Czech Republic.
The ossuary is estimated to contain the skeletons of between 40,000 and 70,000 people, whose bones have, in many cases, been artistically arranged to form decorations and furnishings for the chapel.