Howard Hughes was once the richest man in the world-he was also one of the strangest, a complete recluse for the last 20 years of his life.
Hughes died more than a quarter-century ago, but, as correspondent Lesley Stahl first reported back in 2003, his vast fortune is still making a powerful impact on the world.
In suburban Washington, D.C., hidden behind trees so big and signs so small that even some neighbors don't know it's there, is the Howard Hughes Medical Institute - one of the richest and quietest charities ever created.
How large is the endowment? Tom Cech, the institute's president, says it's $11 billion, making the Hughes Institute the second-largest philanthropy in the country, behind Bill Gates' foundation.
The institute's mission: to unlock the secrets of life. Hughes funds hundreds of the best biologists and geneticists in America.
Some of its great discoveries include: the discovery of the genes responsible for cystic fibrosis; muscular dystrophy; a non-invasive test for colon cancer; a new drug that fights leukemia; breakthroughs in AIDS research; work that may lead to a cure for spinal cord injuries; and much more.
All of these discoveries were made by "Howard Hughes investigators." There are 303 in the U.S., and they're the cream of the scientific crop and include 12 Nobel Prize winners at the moment. Tom Cech won his own Nobel for his work on RNA.
How much does Howard Hughes spend a year funding all these projects? "It's about a million dollars per investigator per year. About $450 million a year," says Cech. "Who would have thought that the Howard Hughes fortune would end up supporting biomedical research?"