if at all possible, check to see how old the buildings/property is. My dad noticed that my first apartment was from at least the 1960s or 1970s because of how high the light switches were (it was before regulations that required those to be handicap accessable). Also when I started putting furniture in, I put a shelf against one wall near a hallway and the wall was slanting inward, which I wouldn't have noticed if not for the shelf