LONDON (AP) _ It's in one of the trendiest parts of London. It's got three bedrooms. And Princess Diana said she spent the happiest days of her life there.

Now, the apartment that Diana shared with three girlfriends before her engagement to Prince Charles is up for sale.

Prospective buyers will get a chance to look at the late princess's prenuptial apartment, in Knightsbridge, next Monday and Wednesday.

Real estate agents John Taylor already have been flooded with calls _ despite an asking price of $738,000.

Because of the huge interest, the current owners, who did not want to be named, have pledged to donate 10 percent of anything above the asking price to the Diana, Princess of Wales Memorial Fund.

The luxury apartment in the Edwardian building was a coming-of-age present from Diana's parents in July 1979. She charged her friends $29.50 a week in rent and emblazoned the words ``Chief Chick'' on the door of the master bedroom where she slept, so no one would forget her landlady status.

Describing the apartment in Andrew Morton's book ``Diana, Her True Story,'' the princess said: ``I laughed my head off there.'' She once said her happiest days were spent at the apartment.

Her romance with the heir to the British throne blossomed while she lived in the apartment. And she stayed there until the night before her engagement was officially announced in February 1981. She then moved into Clarence House, Queen Mother Elizabeth's London home.

After Diana's wedding in July 1981, her mother, Frances Shand Kydd, sold the apartment to Japanese buyers for $164,000, twice what she had paid for it. The current owners, an oil executive and his wife, have lived there with their two children for six years.

Diana and Charles divorced in 1996, and she was killed the following year in a car crash in Paris.