if the art in this place is worth 20+ billion dollars

I was wondering the same thing. They made it a point of showing the various forms of decay taking place in the old building (some of which may have been exaggerated as part of the overall ploy to get the artwork into the *safety* of a big museum in a nearby city). I was amazed that such a collection, sitting in an old building, and having a value purportedly in excess of many billions of dollars, did not attract the attention of art thieves starting from about the early sixties when artwork such as this really started gaining attention, and started being sought after by the art collectors of the world - some of whom are not above buying a purloined piece.