It’s absolutely real, which is kinda the point of the post. My uni had a whole lot of these books for tons of different subjects. The ones I walked around the most were history-focused, with huge maps and elaborate details. I say walked around, because it felt like you were in a small forest since the books are the size of little trees. Maybe that’s why most of the were at the end of sections or in the back corners of the stacks, because they’re so hilariously unwieldy compared to modern books.

Without more research I can only speculate as to why they were made so large, but I’d bet many of them were written prior to the widespread adoption of the printing press, and before paper sizes were standard. And if a book is only going to be used by a few select people, and always in the same building, there’s not much utility in making it portable.