The mausoleum "Octahedron" was constructed in the 1430s-1440s, at the time of Mirzo Ulugbeg. The remains of the mausoleum are represented by octahedral pavilion without a dome, with through lancet arches at the sides. Facets of rotunda are coated with brick mosaics; tympans - with carved composed mosaic. Painting on ganch in bluish – dark blue palette decorates the interior. Under the floor there is a faceted crypt with ground graves. There are four unknown female depositions. Architecturally, "Octahedron" is close to the tower mausoleums in Iran and Azerbaijan, what gives a reason to assume participation of masters from these countries.