The SIS Building or MI6 Building at Vauxhall Cross houses the headquarters of the Secret Intelligence Service (SIS, MI6), the United Kingdom's foreign intelligence agency. It is located at 85 Albert Embankment in Vauxhall, a south western part of central London, on the bank of the River Thames beside Vauxhall Bridge. The building has been the headquarters of the SIS since 1994. History Background Previously based at 54 Broadway, the SIS relocated to Century House, a 22-storey office block on Westminster Bridge Road, Lambeth, near Lambeth North and Waterloo stations, in 1964. Its location at Century House was classified information, though The Daily Telegraph reported that it was "London's worst-kept secret, known only to every taxi driver, tourist guide and KGB agent". Century House was described as "irredeemably insecure" in a 1985 National Audit Office (NAO) report with security concerns raised in a survey; the modernist building was made largely of glass, and had a petrol station at its base. Security concerns combined with the remaining short leasehold and cost of modernising the building were important factors in moving to a new headquarters. Design and construction The site on which the SIS building stands had been the location of the Vauxhall Pleasure Gardens in the 19th century. Several industrial buildings were subsequently built on the site after the demolition of the pleasure gardens in the 1850s, including a glass factory, a vinegar works and a gin distillery. Archeological excavation of the site during building found the remains of 17th-century glass kilns, as well as barge houses and an inn called The Vine. Evidence was also found for a river wall on the site. In 1983 the site was bought by property developers Regalian Properties. A competition to develop the site was won by architect Terry Farrell, with an urban village as Farrell's original proposal. A scheme of office blocks was subsequently developed for the site, with a government agency as their occupier. The building had been sold for £130 million in 1989, with construction planned to take three years, built by John Laing. SIS ultimately became the occupiers of the building. Farrell's design for the building was influenced by 1930s industrial modernist architecture such as Bankside and Battersea Power Stations and Mayan and Aztec religious temples. Regalian approached the government in 1987 to assess their interest in the proposed building. In 1988 Prime Minister Margaret Thatcher approved the purchase of