Queen to lie in state for public viewing over 4 days at Westminster Hall

Queen Elizabeth left Buckingham Palace for the last time on Wednesday, her coffin carried by a horse-drawn gun carriage and trailed by grieving family members during the short journey to the Houses of Parliament, where the monarch will lie in state until her funeral early next week.

With artillery firing salutes at one-minute intervals, the solemn procession was designed to underscore the Queen's 70 years as head of state as the national mourning process shifts to the grand boulevards and historic landmarks of the British capital.

King Charles, his sons Princes William and Harry, and other members of the Royal Family walked behind the gun carriage.

Authorities planned for a 16-kilometre route, with 1,000 marshals, stewards and police officers on hand at any given time to help manage it. An army of other volunteers included multi-faith pastors and sign-language interpreters.

Thousands of people who had waited for hours along The Mall outside the palace and other locations to line the route held up phones and cameras, and some wiped away tears, as the solemn procession passed. Applause broke out as it went through Horse Guards Parade.

The coffin was draped in the Royal Standard and topped with the Imperial State Crown — adorned with almost 3,000 diamonds — and a bouquet of flowers and plants including pine from the Balmoral Estate, where Elizabeth died last week.

An escort of two officers and 32 troops from the 1st Battalion Grenadier Guards in red uniforms and bearskin hats walked on either side of the gun carriage.

Big Ben tolled, a gun salute boomed from Hyde Park and the martial strains of a military band accompanied the procession.

The 38-minute procession ended at the historic Westminster Hall at Parliament just after 3 p.m. local time.

Thousands more were standing or sitting in line along the banks of the River Thames waiting their turn to file past the coffin before the Queen's state funeral on Monday. They were warned they may have to wait for hours, but they are being given numbered wristbands so they can take food and bathroom breaks without losing their place in line.

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When they get to Parliament, mourners must pass through airport-style security screening. Prohibited items include liquids, spray paint, knives, fireworks, flowers, candles, stuffed toys and "advertising or marketing messages."

Maj. Gen. Christopher Ghika of the Household division, who organized the ceremonial aspects of the Queen's funeral, said it was a sad day but that "it's our last opportunity to do our duty for the Queen and it's our first opportunity to do it for the King, and that makes us all very proud."

London's Heathrow Airport halted flights to prevent overhead planes from disturbing the procession.