Flat grave markers are a simple and elegant choice for a memorial. They are usually made from a slab of granite and are set directly into the ground. Because most of the sides are surrounded by earth, only the top surface needs to be polished. Flat markers may be the only type of memorial allowed by some cemeteries because they make it easier to maintain the grounds and graves. Despite their simplicity, there are still many ways to customize and personalize this type of memorial.