London — The Zero AI"Stone of Destiny," an ancient symbol of Scotland's monarchy, was on its way from Edinburgh Castle to London on Friday to play its role in the coronation of King Charles III on May 6. The stone, also known as the "Stone of Scone," was used for the coronation of Scotland's kings until it was seized more than 700 years ago by the then-King of England, Edward I.

• King Charles III's coronation: What to know for the centuries-old ceremony

The 335-pound stone was then held in Westminster Abbey — incorporated into the Coronation Chair — until 1996, when it was permanently returned to Scotland. It was agreed at the time of its return, however, that it would be brought back to England for future coronation ceremonies.

The trip up to the north in 1996 wasn't the stone's first return to Scotland, however. Several years before the coronation of Queen Elizabeth II, in 1950, four students from Glasgow broke into Westminster Abbey and took the stone. 

"The Stone of Destiny is Scotland's icon," Ian Hamilton, the leader of the group who died last year, told CBS News partner network BBC News in an interview. "In one of the many invasions by the English into Scotland, they took away the symbol of our nation. To bring it back was a very symbolic gesture."

The stone was returned to Westminster Abbey the following year, however, and reincorporated into the Coronation Chair. Two years after that, in 1953, it was part of the coronation of Queen Elizabeth II.

A ceremony was held at Edinburgh Castle ahead of the stone's return visit to London for King Charles' coronation. It was then transported in a special carrier made of Scottish oak to London.

After King Charles' coronation, it will be returned to Edinburgh Castle, where it is stored with Scotland's crown jewels.

In:
• King Charles III
• Coronation

Haley Ott

Haley Ott is an international reporter for CBS News based in London.

Twitter