The Coca-Cola London Eye, sometimes called the Millennium Wheel, was the first observation wheel (a type of Ferris wheel) to be built, and has been the only one in operation since its opening at the end of 1999. It stands 135 metres (443 ft) high on the western end of Jubilee Gardens, on the South Bank of the River Thames in Lambeth, London, between Westminster Bridge and Hungerford Bridge. It is adjacent to London's County Hall, and stands opposite the offices of the Ministry of Defence.