Union Pacific Railroad Cheyenne, Wyoming Roundhouse. Base of operations for historical UP steam and diesel locomotives 4-8-4 #844, 4-6-6-4 #3985 (currently the world's largest operating steam locomotive), E9s #949, 951 & 963B , DDA40X #6936 (world largest diesel locomotive) and support equipment. Union Pacific has the only corporate heritage operation of any major railroad. Built in 1932, the roundhouse used to have total of 48 stalls, now only 7 stalls of the old passenger house remain.
Now we know.
It was built in sections through the years and those 7 stalls are actually the last seven that were built.