Devil In The White City

Non-fiction account of

Chicago Worlds Fair (1893) as wrestled into existence by Daniel Burnham (who, among many other things, designed the NYC's Flatiron Building)
activities of Serial Killer HHHolmes in Chicago at the same time

Enjoyed the underlying story of the Fair, but the writing ranges from flat to hugely irritating. The flash-forward tidbits ("only later would the world realize...") are just 1 step above "it was a dark and stormy night".

But recommended by John Walker.