Multiple intersecting corridors filled with doors that have never been opened.
The occasional sculpture of a vaguely defined woman, elevated beyond reach. When I say vaguely defined, I don't mean incomplete, just lacking in detail; as if the sculptor didn't want to get specific, they just wanted to make something feminine.
The colours of the world would alternating between varying shades of grey and blue, with some deep purple thrown in for good measure.
Street signs nailed to the walls at random, some telling you to hurry up, some telling you to go back, some just containing insults.
Columns of bone, fracturing under the weight of the roof, despite it appearing quite easy to support.