The building where maintenance and repairs were done on trains used to be called a roundhouse. Some of them had a turntable inside so they could maneuver the locomotives and cars into position for easy parking for storage or work in one of the open bays. I also think it might have kept the tools and large equipment more centrally available for mechanics. This roundhouse is located in Jamestown Ca at the Railtown Historic Museum. It is still in active operation and maintains and restores their antique train equipment. It remains open through private funding and a wonderful group of volunteer’s after the state closed it down a few years ago. The park offers train rides during the summer, and a Polar Express ride in December. Enjoy your day and stay healthy.