Senlin Ascends (The Books of Babel #1) by Josiah Bancroft
The first book in the word-of-mouth phenomenon debut fantasy series about one man's dangerous journey through a labyrinthine world.
"One of my favorite books of all time" -- Mark Lawrence
The Tower of Babel is the greatest marvel in the world. Immense as a mountain, the ancient Tower holds unnumbered ringdoms, warring and peaceful, stacked one on the other like the layers of a cake. It is a world of geniuses and tyrants, of luxury and menace, of unusual animals and mysterious machines.
Soon after arriving for his honeymoon at the Tower, the mild-mannered headmaster of a small village school, Thomas Senlin, gets separated from his wife, Marya, in the overwhelming swarm of tourists, residents, and miscreants.
Senlin is determined to find Marya, but to do so he'll have to navigate madhouses, ballrooms, and burlesque theaters. He must survive betrayal, assassins, and the illusions of the Tower. But if he hopes to find his wife, he will have to do more than just endure.
This quiet man of letters must become a man of action.