With a three-year-old in the house, I read a ton of children's books. We make a trip to the library at least twice a month, and usually return with at least 10-15 new books.
As a lifelong comics fan, I'm often attracted to books by either creators I know who have done crossover work (i.e. James Kochalka, Jon Muth, Berkely Breathed, Art Spiegelman, etc.) or books that have exceptional drawing styles. A Subway For New York by David Weitzman is one of the best I've come across in a long time.
As the title obviously implies, the book is a meticulously researched story about the building of the New York subway system (or the IRT, as it was originally called). It's at a level of detail well beyond a three-year-old's level of comprehension (more like 8-10 year-olds), but the surgically rendered black-and-white drawings are stunning, reminiscent of classic turn-of-the-century drawings often seen in high-end literary magazines like Scribners or Harper's.
Weitzman's double-page, widescreen images, clearly based on archival photos, give a stunningly clear depiction of the incredible amount of engineering and manual labor that went into the subway's construction. It's a relatively quick read, but you definitely come away with a good understanding of what a monumental accomplishment the subway system was, and just how ingenious and difficult the methods used to dig the tunnels and build the stations and rail system were.
It's amazing that the subway not only still runs 110 years later, but that it transports several million passengers a day; it's literally the heart of the city's circulatory system. As someone who commutes on the subway regularly, it also gave me a whole new appreciation for the system which I so often take for granted.
Anyway, Weitzman's fine book is highly recommended, both for its incredibly detailed and historically accurate line art and its research.