I guess this is a classic.  Mild on science fiction, heavy on historical tourism.  A great read for any New Yorker.  Si Morley, our cool chill protagonist, found languishing in a NYC ad firm in the 70s, gets recruited into a top secret government project to travel back in time.  The G-men decide to send him back to 1882 Manhattan, using the Dakota apartment building as the time machine.

It’s a very clever story, and serves up a wealth of information on life in Manhattan back then.

Students, if you have to read up on the 1880s for class, read this first.  It’s a history book with a plot.  All history books should be written this way.