Subtract a landmark "shape" from parking lot "shape."
Example: Create a parking lot (which usually contains the building, landmark, mall, etc. inside). Now subtract the building shape from the parking lot shape to delineate the different types (landmark and parking lot). Especially useful for malls, and businesses that have lots that wrap around to make awkward shapes.
NOTE: Currently, if you draw a parking lot OVER an existing landmark, it makes the landmark un-selectable.