Opened in June 2016, Tate Switch House is a ten-storey, 65m high tower, built above the subterranean oil tanks of the former Bankside Power Station, itself converted in 2000 into an art gallery by Swiss architects Herzog and de Meuron. Half of the original switch house building was demolished to make room for the tower, which was then rebuilt around it, with large gallery spaces and access routes to Tate Modern’s ‘main building’ (now called the Boiler House) on two levels. The design of the tower, again by Herzog and de Meuron, was first proposed as a glass stepped pyramid, but this was amended to incorporate a sloping façade in brick latticework (to match the original building). The Switch House extension provided an extra 22,500 square metres of exhibition and performance spaces, education facilities, offices, cafes and shops, and the tower is topped by a hugely popular viewing terrace that offers visitors 360-degree views across London. In May 2017 the Switch House was formally renamed the Blavatnik Building, after Anglo-Ukrainian billionaire Sir Leonard Blavatnik, who contributed a substantial amount of the £260m cost of the extension.