The 28th World Science Fiction Convention (Worldcon), also known as Heicon '70, was held on 20âÂÂ24 August 1970 at the Stadthalle Heidelberg in Heidelberg, West Germany.
Manfred Kage eventually became Heicon's convention chairman, the last of more than a dozen fans who briefly held the position during the convention's rocky organizational period.
Attendance was approximately 620.