OrbitalHub

NASA dicit:

​Technicians use massive cranes inside the Vehicle Assembly Building at NASA Kennedy’s Space Center in Florida to lift the fully assembled SLS (Space Launch System) core stage vertically 225-feet above the ground from High Bay 2 to a horizontal position in the facility’s transfer aisle. In the transfer aisle, technicians conducted final preparations of the core stage before it was integrated with the completed twin solid rocket booster segments. NASA is implementing a more efficient stacking process to support future missions to the Moon beginning with the Artemis II test flight.

Video credit: NASA