The death of Queen Elizabeth II set in motion a tightly choreographed series of ceremonial and constitutional steps, as Britain undergoes a period of national mourning and enters the reign of King Charles III.

A long-established 10-day plan, code-named Operation London Bridge, covers arrangements for the Queen’s final journey to London and state funeral.

Here is a look at what will happen in the coming days:

Thursday, Sept. 15

Queen Elizabeth II lies in state in Westminster Hall in London for the first of four full days. Thousands of people joined a huge line to pay their respects to their late monarch. By midday, the queue had grown to 4.4 miles (7 kilometers), winding past Tower Bridge.

Friday, Sept. 16

The King and Queen Consort will visit Wales, the last leg of their royal tour of the four nations that make up the United Kingdom.

On Friday night, the King and his three siblings — Princess Anne, Prince Andrew and Prince Edward — will hold a 15-minute vigil around the Queen’s coffin as she lies in state.

Sunday, Sept. 18

Britain holds a “national moment of reflection” with 1 minute of silence at 8.p.m. (1900 GMT, 3 p.m. EDT).

Monday, Sept. 19

The Queen’s lying in state period finishes early Monday morning.

The King will lead the royal family in a procession that takes the Queen’s coffin from Westminster Hall to nearby Westminster Abbey for a state funeral that begins at 11 a.m. Leaders and dignitaries from around the world, including Prime Minister Justin Trudeau and Governor General Mary Simon, are expected to attend.

Two minutes of silence will be observed across the U.K. at the end of the funeral.

The funeral marks the end of 10 days of national morning, and the day will be a public holiday across the U.K.

A committal service for the Queen takes place at St. George’s Chapel in Windsor on Monday afternoon. She will be interred alongside her late husband, Prince Philip, in the chapel in a private service later that night.

(The Associated Press)