Hexadecachoron

In a world with four spatial dimensions, for example, we can construct only six regular solids, viz pentatope, tesseract, hexadecachoron, icositetrachoron, hecatonicosachoron and hexacosichoron.

We have chosen the surfaces of a pentatope (5-cell) as well as a hexadecachoron (16-cell), which are simple standard triangulations of a 3-sphere, shown in figure (7), as our underlying lattices.

In four dimensions, surprisingly, there are three space-filling convex regular polychora: the tesseract (the hypercube in ℝ⁴), the hexadecachoron, and the icositetrachoron.