A 220-year-old time capsule containing coins, documents and other artifacts left by US founding fathers Samuel Adams and Paul Revere was opened by Massachusetts officials on Tuesday.

"The history of Massachusetts is the history of America," Secretary of the Commonwealth William Galvin said before the box was opened, adding the items were symbols of the "great hope" of the country's founders.

The corroded 10-pound (4.5-kg) brass box, removed frombeneath the state house last month, was painstakingly dismantled and unpacked by custodians at Boston's Museum of Fine Arts in a gallery hung with oil portraits of both men.

Among the items in the box were two dozen coins including a 1652 Pine Tree Shilling struck by colonists in defiance of England, a bronze medal portraying George Washington, a silver plate made by Revere, and colonial records and newspapers.

Galvin said he expected the items would be displayed at the museum for some time before being placed back beneath the state house cornerstone, possibly with additional items from this era. 

The capsule was first placed under the cornerstone of the 18th-century state house building, a Boston landmark topped by a gilded copper dome made by Revere's company, on July 4, 1795 in recognition of America's 20th anniversary of independence.

Adams was then governor of Massachusetts, and Revere a  olonial icon and silversmith best known for alerting Colonial fighters to the approach of British Forces before the battles of Lexington and Concord in 1775.

The unveiling marked the first time its contents have been seen publicly since 1855, when it was also removed from the  cornerstone, the items inside cleaned, and other items like newspapers and coins added.

The capsule is more than a century older than a 113-year-old one discovered inside a lion atop Boston's Old State House last year. That capsule included materials from the presidential campaigns of William McKinley and Theodore Roosevelt.

(dna)