As part of a two-year international tour aimed at raising $100 million for charity, a show featuring 20 gowns worn by Princess Diana was beginning a monthlong stay today in the nation's capital.

The gowns glitter under spotlights in glass cases spread around a darkened room. Large wall captions and bigger-than-life photos illustrate her life and work.Contributors paid $500 a person to attend a gala Thursday night in the great glass-covered atrium of the new Ronald Reagan Building. The regular exhibit will cost $12.50 a person.

Maureen Rorech, who runs a chain of dress shops based in Tampa, Fla., bought 13 of the dresses for $870,000 last year at a New York auction. She later bought a 14th and borrowed six others for the show.

Rorech has organized a not-for-profit sponsor, The People's Princess Charitable Foundation Inc., to take the gowns around the world, ending in London in 2000. At the end of the tour, she plans to give 13 of the dresses to Diana's sons, Princes William and Harry.

The show has already been to Athens, Ga.; Lexington, Ky., and three Florida cities. In Miami, it grossed $100,000 in two hours, she said. Proceeds go to cancer and AIDS research, Boys and Girls Clubs of America and the American Red Cross.