I am looking for the route of Imola's Tre Monti Circuit that was used for a couple of races in the 20s. G. de Carli gives only distance figures and the location of the start for one variant.
What makes finding material on the 1920s races difficult is that a route with the same name was used as a cycling stage in the 1960s. So the only route I could find was one for cyclists, but it includes the current racetrack, which is a bit anachronistic. Removing the circuit, i.e. going from Variante Alta straight to Rivazza, gives a distance of 12km, which is close to one of the 1920s' variants.
So the questions now are, is the modern cycling route the same as the 1920 Tre Monti circuit, and how do the two 1920s variants differ from each other?