The Como Roundhouse was built by Italian stonemasons in 1881, along with a depot, which was built in 1879, and the Gilmore Hotel, completed in 1880. So, what exactly is a railroad roundhouse? A roundhouse is a building with a circular or semicircular shape used by railroads for servicing and storing locomotives, and usually surrounds, or is next to, a turntable. Early steam locomotives normally only traveled forward, and later locomotives often could not operate as well in reverse. Turntables allowed locomotives or other railroad rolling stock, such as freight and passenger cars to be turned around for the return journey, and roundhouses, designed to radiate around the turntables, were built to service and store these locomotives.