Brian Eno: Ambient 1: Music for Airports (1978)
And this is where the whole ambient movement began, when Eno in a hospital bed could only partially hear music playing which lead to Discreet Music (1975) then functional ambient music for specific sites. Like an airport. Music which is as ignorable as it is enjoyable.
Next: Brian Eno: Ambient 2; The Plateau of Mirror and Apollo; Lou Reed, Hudson River Wind Meditations; Aphex Twin, Selected Ambient Works Vol II