ITV News reports on the crowds queuing to see the Queen Mother Lying in State in 2002.
Westminster Hall has been used for royalty and former primer ministers to lie in state seven times in history with the latest being 20 years ago for Queen Elizabeth, the Queen Mother.
Queues stretched for miles to see the Queen Mother's coffin over a three-day period after she died on Saturday, March 30, 2002, aged 101.
Westminster Hall became the designated site for Lying in State at the end of the 1800s with Prime Minister William Ewart Gladstone the first to do so.
The Duke of Edinburgh did not lie in state following his death last year in accordance with his wishes.
All seven previous occasions are commemorated by tablets on the floor of Westminster Hall.
In plans for the Queen's Lying in State, the last gun salute will sound as her coffin is carried to the doors of Westminster Hall.
Mourners were encouraged to continuously move as they paid their respects in an attempt to reduce waiting times.
For the Queen Mother's Lying in state, her four grandsons stood by her coffin in an act called the Vigil of the Princes.
Other members of the royal family are likely to attend the Queen's Lying in State, witnessing the lines of mourners, just as they did for the Queen Mother.
Unlike the scenes currently greeting the Queen's movements ahead of her funeral on Monday, there were fewer phones and more newspapers to be seen twenty years ago.
After her death in March 2002 around 200,000 people waited in line to file past the Queen Mother's coffin and pay their respects.
The management of the queues outside is codenamed Operation Feather.
While Westminster Hall is set to open 24 hours a day, authorities are warning mourners to prepare for hours of standing with little chance to sit down.
The Queen Mother lay in state for three days at Westminster Hall before her funeral in Westminster Abbey on April 9, 2002.
The Queen's state funeral will take place at Westminster Abbey in central London at 11am.
The remarkable life of the Queen remembered in our latest episode of What You Need To Know