Updated

A colossal panoramic painting depicting the Battle of Atlanta from the American Civil War is moving from the building where it's been displayed for nearly a century.

Historians say moving the 6-ton Cyclorama — one of the nation's largest paintings — from Grant Park to the Atlanta History Center across town marks a major milestone in its restoration.

The move is to begin Thursday and take two days.

History Center spokesman Howard Pousner says the process will slow to a crawl if weather or anything else endangers the 15,000-square-foot painting.

The painting, created by German artists at the American Panorama Co. in Milwaukee in the 1880s, is one of only two of its kind on display in the nation. The other is at Gettysburg National Military Park in Pennsylvania.