In the 1920s the urban core of Dessau was bound by the Mulde River to the east and the railroad tracks to the west. When Fritz Hesse, the liberal mayor of the city, invited Gropius to move the Bauhaus to Dessau, he sweetened the deal with the funds for a new building. And he gave Gropius--or did Gropius choose it?!--a plot of land literally on the wrong side of the tracks, several blocks west of the train station, along Friedrichs Allee (now appropriately named Gropius Allee.)
Earlier today we had a long conversation about the Bauhaus building with the students here, and some of them found out that the site was originally was not one but two plots separated by a small road (now called Bauhausstrasse) perpendicular to Friedrichs Allee. Add to the bargain that Hesse included a separate vocational school (Gemeinschaftsgebäude der Kunstgewerbe- und Handwerkerschule) in the program and you have a pretty complicated starting point for project.
So, what does Gropius (or Carl Fieger, or whomever was working on the project) does? He deploys three major rectangular volumes, almost as a child playing with wooden blocks: the workshop volume--the Bauhaus proper--oriented north-south along Friedrichs Allee, the volume of the vocational school oriented east-west along the road to the train station, and a third volume of studios, smaller in plan but quite taller than the other two. That sets the game for two other moves, both of them bridges you could say: one a single-story volume--housing the auditorium and the refectory--between the workshops and the studios, and the other actually a two-story bridge of offices spanning between the workshops and the vocational school.
Today, the Bauhaus is very much embedded into the fabric of the city, but in 1926 it may have appeared like a very large thing in the middle of nowhere. I like to think of it as a foundational gesture for the western expansion of Dessau, a major piece of urban architecture "in active voice."