Spatial memory is a powerful way for users to become expert with an interface, because remembering item locations means that users do not have to carry out slow visual search. Spatial learning in the real world benefits greatly from landmarks in the environment, but user interfaces often provide very few visual landmarks. In this paper we explore the use of artificial landmarks as a way to improve people's spatial memory in spatially-stable grid menus called CommandMaps. We carried out three studies to test the effects of three types of artificial landmarks (standard grid, simple anchor marks, and a transparent image) on spatial learning. We found that for small grid menus, the artificial landmarks had little impact on performance, whereas for medium and large grids, the simple anchor marks significantly improved performance. The simple visual anchors were faster and less error-prone than the visually richer transparent image. Our studies show that artificial landmarks can be a valuable addition to spatial interfaces.