What is the Oldest Book you’ve ever read?

I would ask you not mention books we were all required to read in school/college, such as “Canterbury Tales”, “Beowulf”, Shakespeare, etc.
I have a book printed in 1867 that I’ve had in my possession for years (I rescued if from the dumpster behind my hometown’s public library). It’s about the US Civil War and I’ve been using it as “decoration” in my living room. I was thumbing through it the other night snd happened to think, “This might be one of the oldest I’ve ever read, if I read it.”
I’m going to have to put some thought to this question to determine what is MY oldest book.

by bchath01