The restored exterior panels, including ones portraying Adam and Eve, will be separated into pairs and presented in the museum, next to similar or contrasting works by other artists of the period, like Fra Angelico and Masaccio. Most of the altarpiece’s front, including the “Mystic Lamb” panel and the unrestored top panels, will remain in the cathedral. (One of the original lower panels, known as the “Righteous Judges” panel, was stolen and continues to be missing; it is represented by a copy.)

“The last time two panels of the altarpiece, Adam and Eve, were shown in a museum was in 1902,” Frederica van Dam, a co-curator of the exhibition, said. “When they depart back to the cathedral, you’ll have this distance again. To have an exhibition where you can see them so close is so extraordinary, to be able to see all the wonderful details.”

It’s the details that may stir the most discussion, as shown already by the recent social media excitement. The restoration of the altarpiece, which began with a study of the painting by a consortium of international experts in 2012, has revealed that a substantial amount of it was reworked in the 16th century, about 120 years after it was originally painted.

“Basically, we have been looking at a masterpiece by someone else,” Ms. van Dam said in an interview at the museum.