Jonathan Jones's top 10 art shows of 2015

Jackson Pollock’s dark years, Mat Collishaw’s monstrous animations, Bridget Riley’s debt to Seurat and Goya’s terrifying imaginings: all were wonderful but topping the list is a brilliant portal on the prehistoric imagination – Celts• More on the best culture of 2015
I loved this exhibition. It’s the first show that has made perfect use of the British Museum’s huge new exhibition space (although Defining Beauty, the blockbuster about Greek art, was