I purchased a copy of Incarceron, by Catherine Fisher.

Description from Goodreads:
Incarceron is a prison so vast that it contains not only cells and corridors, but metal forests, dilapidated cities, and wilderness. It has been sealed for centuries, and only one man has ever escaped. Finn has always been a prisoner here. Although he has no memory of his childhood, he is sure he came from Outside. His link to the Outside, his chance to break free, is Claudia, the warden’s daughter, herself determined to escape an arranged marriage. They are up against impossible odds, but one thing looms above all: Incarceron itself is alive . . .

Review:
Soooo, what to say about Incarceron? It’s good. The writing is stellar. The idea is big and interesting. I appreciate the world-building and the characters. But I felt like I’d been reading this book for 15 years, instead of a week. A lot happens, don’t get me wrong. But it just felt really slow. I’ll read book two at some point. I want to see what happens. But I’m gonna give myself a break from it first.