I remember the story about the map from some original Quake 1 episode.
It was made too complex to meet the average 90s home PC requirements so it was cut down in size, polygons and complexity.
But I’m sure that this map existed and I even played in it.
I hardly can remember some quite long white brick ladder placed at the edge of big cavern which floor was filled with water 
Don’t blame me hard, it was about 15 years ago
Could somebody point me to the right direction?
Yeah, definitely!
Thank you very much, Spirit!