Endless Stair at London Design Festival

One of the highlights of the weeklong London Design Festivalnbsp;(14-22 September) is the Endless Stair, which occupies the lawn in front of the Tate Modern until 10 October. London's dRMM was obviously inspired by M.C. Escher in their design, which entices people to move up and down various stair runs to find the high point and its lookout.