Emil Ritterling's Legio

In 1925 the german scholar Emil Ritterling published his article 'legio' in part 12 of the Realencyclopädie of Klassischen Altertumswissenschaft. At that time, iIt was the definitive history of the legion in Roman history and consisted of a lengthy history of the concept of the legion, followed by an even longer detailed description of the history of every single known Roman imperial legion. The total 'article' came to 651 columns in the encyclopedia.
Despite its age, it is still considered the starting point for research of individual legions and only very recently has an 'update' appeared in the form of Le Bohec's conference report 'Les Legions de Rome sous le Haut-Empire' (Lyon 2000).
The Realencyclopädie is in early 20th century German and usually only available in university libraries. To make it more easily accessible, Romanarmy.com has started a project to translate it and make it available online!
(Related site: Livius.org)