Jungle of Stone: The True story of Two Men, Their Extraordinary Journey, and the Discovery of the Lost Civilization of the Maya
Jungle of Stone has mysterious lost cities, jungles, revolutions, intrepid explorers, and a touch of international rivalry. What more could you ask for?
Oh, and it's also pretty well written. It doesn't quite have the driving novel-like pace of, say, The Lost City of Z, but its more informative overall. The illustrations, from one of the titular Two Men (Frederick Catherwood), are flat-out gorgeous. My only gripe is that the information on the Maya themselves is confined to one chapter; I'd have traded a bit of the travel narrative for some more data.
The aforementioned The Lost City of Z by David Grann is a great, quick read. Alexander von Humboldt makes a couple of appearances here, as well. On a slightly different note, Michael D. Coe's Breaking the Maya Code is a must-read for anyone interested in ancient writings and their deciphering.