The Euclidean realm is a flat, infinitely large three-dimensional space that follows the rules of Euclidean geometry. It can be created by taking the cartesian product of three copies of the Euclidean line. A realm can be used to bisect a teron, and polychora can have realms of symmetry through which they can be reflected. Taking multiple realmic cross sections of a polychoron can give insight into their structure; this is one method that can be used to visualise polychora without needing to picture a four-dimensional space.