The Gagosian had bought the piece from Maya Widmaier-Picasso in 2015 and sold it to Mr. Black; but the Qatari royal family said it bought the work in 2014.
An installation at the Venice Architecture Biennale shows how the death camp was designed.
The new 10-story wing of a London museum that attracts millions each year promises a fresh way to see art.
A master of the wordless visual gag, Mr. Kovarsky produced nearly 40 covers for the magazine and 300 cartoons, each with a subtle, intellectual twist.
Using technical and artistic ingenuity, planners created interior stages for theater, dance and music in a way that invites brainstorming about the plant’s future.