Museums Facts

A retired gardener borrowed a metal detector in 1992 to find a lost hammer in a Suffolk field. Instead, he uncovered 14,865 Roman coins and 200 pieces of ancient jewelry - the largest late Roman treasure hoard ever found in Britain, valued at £1.75 million. They found the hammer too. It's in the British Museum.

The Lincoln Memorial has a secret: a 43,800 sq ft cave beneath it - nearly twice the floor space of the memorial above. Rainwater seeping through the marble has grown real stalactites, and 1914 construction workers left cartoon graffiti on the columns, now preserved behind plexiglass. It opens as a public museum for the first time on June 25.

A Virginia woman bought a napkin-sized landscape at a West Virginia flea market in 2009 for $7. She wanted the plastic cow and the doll in the same box. Two years later she learned the little painting was a genuine Renoir worth $100,000. Then the FBI showed up. The museum had reported it missing in 1951.