I've been wanting to read The Devil in the White City for ages. It's one of those books that everyone raves about and that has jacket blurbs touting that it's nonfiction that reads like fiction. It didn't quite live up to all that hype for me, but it was still one of the most readable nonfiction books I've read.
Set in the late 1800's, it tells the parallel stories of the architect who planned and built the Chicago World's Fair and a serial killer who lured his victims from innocent out-of-towners who came to Chicago for the fair. The serial killer half of the book is very creepy and macabre, and has a similar feel as The Alienist. On the World's Fair half, I found it pretty fascinating that they spent years building a massive, temporary, Disney Land-like place, ran it for six months, and then closed it down. All in all, a very interesting book.