A tornado shelter and having a reinforced monolithic construction resulting from a single pour of concrete is described herein. Rebar extends upwardly from a base. The rebar is encased in concrete that forms the walls of the shelter. An upper portion of the rebar extend above a top surface of each of the walls. The upper portion of each of said rods are bent inwards and are also encased in the single pour of concrete for strengthening a ceiling portion of the shelter. A door, in-wall conduits, vent orifices and attached benches may also be provided.