Cadbury Schweppes has apologised to the authorities in the US city of Boston after a marketing stunt closed an historic cemetery.
The coin was hidden behind a stone slab in the cemetery
The UK firm was promoting its Dr Pepper drink in the US by organising gold coin treasure hunts for big cash prizes.
Contestants flocked to the 347-year-old Granary Burying Ground to find the hidden coin, but the site was shut amid fears that graves may be desecrated.
The firm said burying the coin there had been "poor judgement".
Cadbury Schweppes communications director Andrea Dawson-Shepherd said: "It was not an appropriate place to bury a coin. It was poor judgment and we have apologised to the authorities. No damage was done to any of the graves."
The campaign had challenged the public to find the coins by issuing a series of clues. An agency hired by Cadbury chose the historic cemetery site.
John Hancock, Paul Revere and Samuel Adams are among historic figures buried in the Granary Burying Ground, which is visited by thousands of tourists every year.
Boston Parks Commissioner Toni Pollak told the Boston Globe: "It absolutely is disrespectful. It's an affront to the people who are buried there, our nation's ancestors."
A Houston woman found the promotion's most valuable coin, redeemable for £760,000, near the Spirit of Confederacy statue in Sam Houston Park, Cadbury said.