One of the worst things about GTA is that you can walk down the street and view all the wonderful buildings but never go into them. Luckily, NewTheft has created a mod that opens up most of the buildings across Los Santos for your viewing pleasure.

They even incorporated working elevators in a few buildings so you can all the floors. This mod even adds each opened location on the map with a marker along with marking which ones are able to be robbed. Check out his page for information on all the buildings that are able to be entered. There are a lot of them.