Early steam locomotives normally traveled forwards only. Although reverse operations capabilities were soon built into locomotive mechanisms, the controls were normally optimized for forward travel, and the locomotives often could not operate as well in reverse. Some passenger cars, such as observation cars, were also designed as late as the 1960s for operations in a particular direction. Turntables allowed locomotives or other rolling stock to be turned around for the return journey, and roundhouses, designed to radiate around the turntables, were built to service and store these locomotives.