What was on the ceiling.
My first home in Austin can best be described as a roach-infested hovel with benefits – It was directly across the street from the UT campus.
It cost me $40 mo. and consisted of a single living area with a bare bulb outlet in the middle of the 7 ft. high ceiling, a full bath, and a kitchen that seemed to me a re-purposed closet. One day, I got so bored that I decided to decorate the ceiling and using green twine and pushpins created an 8 ft. by 8 ft. version of this pattern centered on the electric outlet which held the bare bulb in the middle of the room.
If you stare at it for a while, it can seem to change from concave to convex and vice versa.
With such a low ceiling, first-time and even some second-time visitors would automatically duck as they came in the door…