The Lloyd's building, Richard Rogers' hi-tech landmark in the City of London, will open to the public for one day as part of its 40th anniversary celebrations and London's Open House festival. It is the first time the building has admitted visitors since 2014, offering a rare chance to see the interior of a structure whose futuristic, inside-out design has divided opinion since it opened in 1986, having been likened to a monster, an oil rig and even the Parthenon.

Free tickets are released on 19 August for the single open day on 19 September, with tours taking in the underwriting room and the historic Adam Room, plus insight into the building's design. Famous for its exposed concrete frame and six external steel towers housing lifts, staircases and ducts, Lloyd's became the youngest building ever to receive Grade I-listed status in the UK in 2011. Festival director Celia Mead described it as "a masterpiece of radical, inside-out architecture" reflecting London's confidence, noting its double-height trading floor and galleried atrium beneath a barrel-vaulted roof 14 floors up.