Rules: only places that don’t exist, so no “NY from Spider-Man” also if you can limit to a building or little town, not an entire city or map.
My pick: The Spencer Mansion from 1996 Resident evil. I always loved that place. Of course without the creatures.
Panau in Just Cause 2. Minus the bad guys of course. I spent a lot of time just traversing that place for fun.