And then I went to this museum but it was locked so I asked a man nearby who looked like he might have something to do with the church, he whipped out his mobile, made a call and two minute later a priest arrived to give me a personal conducted tour. He said that the book is the oldest printed book in the world but I don't think that can be true. He also told me that the language is Slavic. I asked if he could read it and he immediately started in that sing song droning chant that priests do. Very entertaining, and he grinned because he could see I was amused. You can see him at the top of the steps.