So, people often talk about how inventive Star Trek
was with the minimalist western set in "Spectre of the Gun", what with partial walls and vague impressions of buildings instead of having actually built the things.
So, imagine my surprise when I stumbled upon a clip of a second season Lost In Space
episode titled "West of Mars" in which the alien "west" set is...
...a bunch of incomplete walls and a limbo background.
Mind you, this aired on 30 November 1966. "Spectre" aired on October 25, 1968 23 months after "West of Mars".