Famous for his public pyrotechnics, Cai Guo-Qiang’s gunpowder and ink work on paper depicts the view from space by aliens of his actual performance explosion at the Great Wall of China. 'Project to Extend the Great Wall of China by 10,000 Meters: Project for Extraterrestrials No. 10' explores the notion of the Great Wall as a symbol of division and boundary, juxtaposed with the original performance piece, which brought people together from around the world. It is a highlight of Sotheby’s upcoming Contemporary Art Evening Sale (31 March, Hong Kong).