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

The corroded 10-pound (4.5-kg) brass box, removed from beneath 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.