LONDON (AP) - Thousands of mourners lined up through the night to file past the coffin of Queen Elizabeth II in Parliament’s Westminster Hall on Thursday, as King Charles III spent a day in private to reflect on his first week on the throne.

The queue to see the queen lying in state stretched for nearly four miles past Tower Bridge. The line snakes along the south bank of the River Thames and then over a bridge to Parliament. Thousands in the line didn’t mind the hours of waiting.

“I’m glad there was a queue because that gave us time to see what was ahead of us, prepared us and absorbed the whole atmosphere,” said health care professional Nimisha Maroo. “I wouldn’t have liked it if I’d had to just rush through.”

After a day of high ceremony and high emotion on Wednesday as the queen was borne in somber procession from Buckingham Palace, the king was spending the day in “private reflection” at his Highgrove residence in western England. Charles has had calls with U.S. President Joe Biden and French President Emmanuel Macron and is speaking to a host of world leaders - many of whom will come to London on Monday for the queen’s funeral.

Heir to the throne Prince William and his wife Catherine, Princess of Wales, will visit the royal family’s Sandringham estate in eastern England to see some of the tributes left by well-wishers.

On Wednesday the queen left Buckingham Palace for the last time, borne on a horse-drawn carriage and saluted by cannons and the tolling of Big Ben, in a solemn procession through the flag-draped, crowd-lined streets of London to Westminster Hall.

Charles, his siblings and sons marched behind the coffin, which was topped by a wreath of white roses and her crown resting on a purple velvet pillow.

The military procession underscored Elizabeth’s seven decades as head of state as the national mourning process shifted to the grand boulevards and historic landmarks of the U.K. capital.

The 900-year-old Westminster Hall is now the focus of events, as the queen lies in state until Monday.

The display of mass mourning is an enormous logistical operation, with a designated 10-mile route lined with first aid points and more than 500 portable toilets. There are 1,000 stewards and marshals working at any given time, and 30 religious leaders from a range of faiths to stop and talk to those in line.

Archbishop of Canterbury Justin Welby, the spiritual leader of the Church of England, wore a high-visibility vest emblazoned with the words “Faith Team” as he spoke to mourners.

Welby, who led a service for the royal family when Elizabeth’s coffin reached Westminster Hall, paid tribute to the queen as “someone you could trust totally, completely and absolutely, whose wisdom was remarkable.”