The White Tower at the Tower of London is thought to date back to 1077 and is one of Europe’s most important monuments. It is believed that originally the south entrance, which is some 6.4 metres above ground level, was accessed from a wooden staircase. The south door was returned to use in 1973 via a wooden staircase after 300 years of disuse, but after 40 years of heavy daily use, it was recognised that it required replacement.