So here's something self-indulgent: the twenty best historical monographs that I've ever actually read that have listings in one of my text file bibliographies. I was going to do something a little more strenuous and go for a top twenty list, but I'm in the midst of moving those over to a more sophisticated format. (Not that sophisticated: the Word2007 Source file system. I sure hope that Microsoft delivers a better version of this that I can transport the data to soon!) So I'd have to hunt down and retype a bunch of titles that deserve to be here. This suggests that the next list should be the even more interesting and eclectic "20 best historical monographs that aren't in my textfile bibliographies for some stupid reason."
I'll get right on that.
Barker, Thomas Mack. Double Eagle and Crescent: Vienna's Second Turkish Siege and Its Historical Setting. Albany: State University of New York Press, 1967. One old fashioned military history. Because it's awesome.
Braudel, Fernand. La Méditerranée et le Monde Méditerranéen à l’epoque de Phillippe II. 2nd ed. Paris: Librairie A. Colin, 1966. Only one Braudel allowed.
Cochrane, Eric. Florence in the Forgotten Centuries, 1527-1800: A History of Florence and the Florentines in the Age of the Grand Dukes. Chicago: University of Chicago Press, 1973. More old-fashioned historiography, and more plainly obsolete; but still a nice read.
James, John. The Paladins: A Social History of the RAF Up to the Outbreak of WWII . London: MacDonald, 1990. It is beyond amazing how one writer can transform a field of study by good use of such a basic research tool.