announced that Laing O'Rourke was the main contractor for the works of the new Leadenhall Building. Throughout 2011, construction began with the basement floors. By December 2012, the steelwork had progressed up to the fifth mega-level, with topping out expected in February or March. The glass cladding had also begun to rise. In May 2013, the co-developers announced that the building was over 51% pre-let. By June 2013, the steelwork of the building was completely topped out with the glass cladding covering almost half the building. The construction of the building was the subject of an episode of the Super Skyscrapers documentary series by the American television channel PBS in February 2014. Tenants The development has succeeded in attracting tenants, especially in contrast to the nearby part-built Pinnacle and completed Heron Tower. In May 2011, it was announced that the lower 10 floors of the Leadenhall Building have been pre-let to insurance broker Aon, which moved its global headquarters to London from Chicago. Insurance group Amlin has also agreed terms on a 20-year lease of the 19th to 24th floors as well as the top floor, the 45th, from March 2015, for a total of 111,000 sq ft of office space. See also City of London landmarks Leadenhall Market List of tallest buildings and structures in London References External links Information on the 1969 building Buildings and structures demolished in 2007 Skyscrapers in the City of London Office buildings completed in 2014 Oxford Properties 2014 establishments in the United Kingdom