(2017) The exhibition at the Park Avenue Armory from 7 June- 6 August 2017, "Hansel and Gretel" was an installation exploring the theme of surveillance.The project, a collaboration of Ai Weiwei and architects Jacques Herzog and Pierre de Meuron, features surveillance cameras equipped with facial recognition software, near-infrared floor projections, tethered, autonomous drones and sonar beacons.