Britain's Queen Elizabeth II has died at the age of 96.
She has been the longest serving British monarch of all time, recently celebrating 70 years on the throne.
Buckingham Palace confirmed the queen's death at her residence in Balmoral in a statement.
She had been placed under medical supervision with doctors concerned for her health, just days after carrying out meetings to transfer power to the new British Prime Minister.
News of the queen's death will trigger an official period of mourning in the UK.
The Prince of Wales has become king, having acceded to the throne immediately on the death of his mother, the Queen.
Charles - the nation's longest-serving heir apparent, having been so since he was three years old - is now fulfilling his royal destiny and reigning as monarch.
The statement from Buckingham Palace in full read: "The Queen died peacefully at Balmoral this afternoon.
"The King and The Queen Consort will remain at Balmoral this evening and will return to London tomorrow."
The flags in Downing Street were lowered to half mast at 6.36pm following the queen's death.