Given as an example of what a rocket scientist thinks of as large by Richard Osborne when Simon Herron asked "...architects are quite good at thinking of large, what do you mean by large?"
'A Dyson Sphere is a hypothetical megastructure originally described by Freeman Dyson (1960). Such a "sphere" would be a system of orbiting solar powered satellites meant to completely encompass a star and capture most or all of its energy output.'
'However, Dyson was not the first to advance this idea. He was inspired by the mention of the concept in the 1937 science fiction novel 'Star Maker by Olaf Stapledon, and possibly by the works of J.D Bernal and Raymond Z. Gallun who seem to have explored similar concepts in their work.'
Search for Artificial Stellar Sources of Infrared Radiation Freeman John Dyson, 'Science', Vol. 131, June 3, 1960, pp. 1667-1668:
Dyson Spheres in popular culture: