Here is the place where post-rock was born. When musical critic Simon Reynolds was writing about Bark Psychosis first album “Hex”, he was amazed and being unable to clasify their music, he called it “post-rock”.
They were mixing rock, jazz, ambient and electronic sounds and in early ’90 that was realy new quality, and for me it still is. Below “Eyes & Similes” from historic “Hex”.

By the way – they started as a Napalm Death cover band :-)