[4] He studied architecture at the Technical University of Munich from 1960 to 1965,[5] and worked with Peter C. von Seidlein [de] for a year after graduation.

[1] In 1966, he went to Chicago to further study architecture under Myron Goldsmith and Fazlur Khan at the Illinois Institute of Technology on a Rotary Scholarship, earning a Master's degree in 1967.

[7][8][9] Generally inspired by Ludwig Mies van der Rohe, yet opposed to the doctrinal application of modernism by his followers, in 1978, Jahn became the eighth member of the Chicago Seven.

[10] Jahn established his reputation in 1985 with the State of Illinois Center in Chicago which prompted him to be dubbed "Flash Gordon".

[62] In 1998, Jahn invited his fellow Vietnam War veteran, George Henry, to race with him in the Waterbury Channel Open.