The 120cell is a regular 4D polytope with 120 regular dodecahedra for sides. This animation shows it projected into our 3D world as it rotates in 4D. Two interlocking rings of ten dodecahedra are shown so you can see inside (the other 100 dodecahedra are hidden). Animation was made using Stella4D software: http://www.software3d.com/Stella.php You can see my paper model of this polytope here: http://www.software3d.com/120Cell.php