Indiana Bell moved a functioning building in 1930

In 1930, the Indiana Bell building - an 8-story steel and brick building built in 1907 - was moved 16 meters to the south, rotated 90 degrees, and then moved 30 meters to the west. The whole task took 4 weeks to complete.

The work was done with such precision that the building continued to operate during the entire duration of the move. A movable wooden sidewalk allowed employees and the public to enter and leave the building at any time while the move was in progress. The company did not lose a single day of work nor interrupt their service during the entire period.

Incredibly most of the power needed to move the building was provided by hand-operated jacks while a steam engine also offered some support. Each time the jacks were pumped, the house moved 3/8th of an inch.

Source: An Incredible Move: The Indiana Bell Telephone Building, AmusingPlanet.com

Here's a non-looping gif I also made: