Longest section - 10 3/8, Widest section - 11", Highest section - 3"." Just like our popular HO model (Item #709), Atlas' new N Roundhouse is based upon a prototypical structure that was once used to house and service locomotives. Molded in appropriate colors, the basic 3 stall kit can be expanded by adding more units. For use with Atlas N Turntable (Item #2790) and Motor Drive Unit (Item #2791), some of our most popular items."