Roman Farm Management (De Agricultura), by Marcus Porcius Cato (20th c. translation), also containing Varro's Rerum Rusticarum Libri Tres: mildly curious in its own right, this also contains recipes for "cheese cake", "must cake", olive salad and cured hams down at the bottom of Cato's book, so it's interesting to us food geeks.
Beaumont and Fletcher's The Spanish Curate is now available in easier-to-read HTML.
For the more serious history student: The Communes Of Lombardy From The VI. To The X. Century (1891).
