In 1930, engineers accomplished something remarkable: they rotated an 8-story, 11,000 ton building a full 90 degrees, in order to allow the construction of a second building on the site (the company needed more office space). Check out a timelapse below by reddit user howmuchbanana:
Located in Indianapolis, the Indiana Bell Telephone Company headquarters was moved 15 inches an hour, all while 600 employees still worked inside. There was no interruption to gas, heat, electricity, water, sewage, and most importantly, the essential telephone service they were providing to the city. A movable wooden sidewalk allowed employees and the public to freely enter and exit the building. The whole move took a month took complete.
According to Amusing Planet, “most of the power needed to move the building was provided by hand-operated jacks while a steam engine also provided some support. Each time the jacks were pumped, the building moved 3/8th of an inch.”
[via u/howmuchbanana, Amusing Planet]