Space Shuttle Main Propulsion Test Article

The Main Propulsion Test Article (MPTA-098) was built by Rockwell International as a testbed for the definitive propulsion and fuel delivery systems for the U.S. Space Shuttle Program. == Description == Never intended for actual spaceflight, the MPTA consisted of the internal structure of a Space Shuttle orbiter aft-fuselage, a truss structure that simulated the basic structure and shape of an orbiter mid-fuselage and a complete Space Shuttle Main Engine (SSME) assembly, including all main propulsion system plumbing and the associated electrical systems.

Source: Wikipedia — Space Shuttle Main Propulsion Test Article (CC BY-SA 4.0)