Digital art group Vertigo have created a new audio-visual installation that reacts to the movement of viewers and passersby, animating a public square with flashing LEDs. The artwork. called Echelon, is located at the foot of London’s Centre Point building and was curated by cultural placemaking agency Futurecity for Almacantar, a development company that is rejuvenating the brutalist building. It takes the form of a 12m (39ft) equilateral triangle of