Queen Elizabeth II, the United Kingdom’s longest-reigning monarch, has died at age 96.

The queen died peacefully at Balmoral Castle in Scotland, Buckingham Palace announced on Thursday, prompting an outpouring of condolences from politicians in the UK and around the world.

The queen spent seven decades on the throne as the UK rebuilt from war, lost an empire, transformed its economy and both entered and left the European Union.

She was a constant presence, the only monarch most Britons have ever known, and she guided the institution of the monarchy through choppy waters.

She likely met more people than anyone in history, and her image, which adorned stamps, coins and banknotes, was among the most reproduced in the world.