On Architecture
Text of the English-language translation of 1826 by Joseph Gwilt, as well as a French translation and the Latin text (Teubner 1899 edition), hosted by Bill Thayer in his Lacus Curtius site.
Plates from Cesariano's Edition of Vitruvius
Woodblock illustrations were added to Vitruvius's text in the edition published by Cesare Cesariano (Como 1521). Images from Art Serve at the Australian National University.
Vitruvius Pollio, The Ten Books on Architecture
The full text of the English translation by Morris Hicky Morgan (1914), hosted by the Perseus Project. Easy navigation through the text; map of sites mentioned.
Vitruvius, On Architecture
12 plates from an 18th-century Venetian edition, hosted by the University of Pennsylvania.