Spatial occupancy issues are discussed. They are important for planning systems and for systems that reason about agents endowed with physical presence moving through two-dimensional space. The author points out that spatial axioms and reasoning techniques are needed for correct description of the fact that an object moving through space occupies a location. The default involved in planning for movement is that, unless we know that a location is occupied, it is free. It is clear that the continuous nature of the space leads to problems with such assumptions. The author points out that careless formulation of occupancy axioms leads to strange side effects. He shows how better axioms can be devised. He also shows how the classical result of Lifschitz on iteration of prioritized circumscription can be used to compute a correct sequence of actions.