However, it did feel like two books were thrown together. It's as though Larson either wanted to write a book about the Chicago World Fair, but he or his editors thought it would be too boring on its own so they threw in the Holmes murders; or he wanted to write about the Holmes killings, but there wasn't enough information about them to fill up a whole book so he filled it out with background on the Fair and it's creators.
It still works really well though, because it's so well written. It may feel like two unrelated books but two very good unrelated books.
The information about the building of the Fair dragged on at times, but it picked up in the second half once the Fair had opened. It was fascinating to read about Holmes and his murders, and how he avoided suspicion for so long.
Creative non-fiction is definitely an art that Larson has flawlessly mastered.