The Burnett Foundation of Fort Worth has been trying since January to sell privately a famous group of sizable bronze sculptures by Henri Matisse, Nu de Dos — or Back I-IV. It’s his sequence of a woman’s back created over 23 years and is considered a landmark work of modernist art. The foundation bought them in 1982, installed them in Burnett Park, but in 2000, when the park was renovated, they were moved to the Kimbell Art Museum.

Sotheby’s failed to sell the four works as a group, however — perhaps because the asking price was reportedly $200 million. But Christie’s successfully auctioned a single one, Back IV, last November for $48.8 million, a record for a Matisse work, in light of which $200 million for the set doesn’t seem outlandish. In fact, that Christie’s sale, says the NYTimes, caused the Burnett Foundation to re-think owning the set: “They realized the value of the four works far exceeded anything that could justify owning them, since its mission is to support health, education, human services and arts initiatives mostly in the Fort Worth area.”

So now Sotheby’s says they’ll auction the works off individually, in chronological order, over the course of the next year. Back I goes up Nov. 2 and is expected to fetch between $20-$30 million.