Symbols - What does heaven look like
One of the advantages of a pyramid symbolically is that it can be made rectangular or square in shape. Both the rectangle and the square are the symbols used to represent the Earth level and layer, as such the positioning ties it symbolically to the Earth, but at higher levels - beyond the normal Earth, Water, Air and Fire levels, the shape may change.
Pyramids are often to be found in Mandalas showing symbolically the path of ascent and the concept of ascension, however, they are shown in two dimensions, which makes them symbolically quite difficult to understand and envisage. You have to imagine them rising from the island in which they are often shown in three dimensions.