People have already started queuing in London to pay their last respects to Queen Elizabeth II when she lies in state from Wednesday 14 September at 5 pm UK time.
Millions are expected to file past her coffin over the four days it's going to be at Westminster Hall near the Houses of Parliament.
Vanessa is one of those already in the queue and she explains what she was told.
"They said it (queue of mourners) might be seven miles (11.2km), we don't know and they might also stop at some point if it's overcrowding. I just wanted to make sure I get the position and get the chance to pay my last respect."
The security operation will be massive, a size not seen before, say police. They'll be tight restrictions - people will only be allowed to carry one small bag.
The new Metropolitan Police Chief, Sir Mark Rowley said it should be a safe event.
"We're going to be putting thousands of officers into this because of the level of security required and the millions of people who want to pay their respects," said Sir Mark.