From 5 p.m. Wednesday, hundreds of thousands of people will gather outside the Queen's coffin in Westminster Hall.
More than 750,000 people are expected in London for what will be the first national tribute since 1965 and the death of Winston Churchill.
To ensure that the tribute to the queen takes place calmly, a strict protocol has been put in place.
Selfies are prohibited, as are candles.
And proper attire is required to be able to come and pray in front of Elizabeth II's coffin.
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But before being able to access the remains of the queen, we will have to be patient.
The authorities are preparing for a long queue of more than 8 km, along the Thames.
So several hundred brave people took the lead and posted themselves by the river on Tuesday evening.
"It's such an occasion, and we're glad we were there all night and would do it again."
The Queen reigned for 70 years and we just gave up one day, and we are more than happy to do so,” says pensioner Suzanne Howell, from Surrey.
In a good atmosphere, hundreds of Britons spent the night to be sure to be the first to say goodbye to the Queen.
“We didn't sleep, but we had a good time.
The camaraderie is out of this world,” says retired Patricia King, from Norfolk.
The coffin of Elizabeth II will be accessible to the public from 5 p.m. until Monday, 6:30 a.m., day of the funeral.
The Palace of Westminster will be open to the public 24 hours a day to accommodate everyone.