The Empire of Death
In 2011, his research and photos were published by Thames and Hudson as The Empire of Death, the title taken from a caption at the Catacombs of Paris, one of the sites included in the book. The book included other famous ossuaries, such as the Sedlec Ossuary and the crypt of Santa Maria della Concezione dei Cappuccini, where he had been granted special permission by the monastery and Italian cultural authorities to photograph. A host of similar, previously unknown sites were also included in the book, however, and the text created a context for understanding the construction of these types of elaborate ossuaries as a Catholic phenomenon that was initiated during the Counter-Reformation.
His book Heavenly Bodies was released in 2013, and delved even deeper into study of obscure macabre art history by presenting the extraordinary story of a group of skeletons taken from the Roman Catacombs in the seventeenth century and completely decorated with jewels by teams of nuns. The book described how these extravagant cadavers, known as catacomb saints, were often mistakenly identified as Early Christian martyrs, then sent primarily to German-speaking lands where they were decorated and placed into Catholic Churches. Such skeletons are scarcely known nowadays, having been mostly removed and destroyed during the Enlightenment, but Koudounaris tracked down all the surviving examples and photographed them for the book. The title received a tremendous amount of press on its release, and Koudounaris was dubbed "Indiana Bones" by the UK press, in reference to his curious and macabre discoveries.