Question: How do you move a fifth-century mosaic that weighs more than four tons? Answer: Verrrrrry carefully, with a lot of engineering know-how.

This spring, the Davis Museum lowered its beloved Antioch mosaic from the fifth-floor wall where it has hung since the 1990s and moved it to a gallery on the second level, where it will be the centerpiece of the newly installed Greek and Roman holdings. The feat was planned and executed by a rigging company, with backup from a structural engineering firm, using chains, pulleys, a specially built steel frame on heavy casters, and other equipment brought into the museum. The entire process took about a week. Originally a floor in an Antioch villa, the mosaic will now be displayed at floor level in the Davis.

The museum’s permanent galleries are currently undergoing renovations. Display space will increase by 100 percent, and objects will be on view that have never been seen by the public. The formal opening of the reinstalled galleries will occur on Sept. 28.