Koons at the Ashmolean: like Popeye giving the Reith Lectures

The Royal Academy has put Bill Viola’s videos next to Michelangelo’s drawings: who wins?

Too many marks, too many colours, too little sense of direction: our critic is underwhelmed by the artist’s clunky, repetitive works

The Turner winner writes loser’s poetry. Oddly, it gives him a special presence

Live conservation is suddenly the hottest thing in the art world — and we have Artemisia Gentileschi to thank for that

The heroic Monarch of the Glen makes Landseer’s grim and compromised career look all the more noble at the National

From Trajan’s Column to Michelangelo’s David, the V&A’s reopened Cast Courts house thrilling full-size replicas of the world’s artistic wonders

Gainsborough was mesmerised by his daughters, and so are we

Tate Liverpool’s Fernand Léger show reveals a jovial French provincial with fluctuating styles and a taste for bulky girls

Think you know Warhol? Think again. The first American retrospective in 30 years reveals a depth to the artist beyond the soup cans and screen prints, says Waldemar Januszczak