A Monet Waterlilies painting not exhibited in public since 1926 and a Stradivarius violin found hidden in a vacant home are among the treasures to be offered at auction from the estate of reclusive heiress Huguette Clark starting next month. 

Christie's will begin a series of sales on May 6 featuring 400 lots of fine art, rare manuscripts and fine musical instruments that Clark and her father, the Gilded Age copper baron, Senator William A. Clark (1839-1925), collected over their lifetimes. The entire sale is expected to generate $70 million.

Miss Clark died in 2011 at age 104. She left conflicting (and contested) wills for her multimillion-dollar estate which included residences on Fifth Avenue in Manhattan; an $80 million+ mansion on a seaside bluff in Santa Barbara, Calif.; and a woodsy chateau in New Canaan, Conn., which sold recently for $14.3 million to desinger Reed Krakoff and his wife. The 14,266 square foot mansion had been unoccupied for 60 years.

Some contents of Clark's homes are now on the auction block. A rare and sought-after Stradivarius violin from 1731 is one highlight. It was discovered by auction staff tucked inside a cupboard. Miss Clark's father bought it for her when she was a teenager. The violin is expected to bring over $7.5 million.

Another gem is a Monet Waterlilies work from 1905 that Miss Clark bought in 1930. Nymphéas hung for 80 years  in the dining room of her grand Fifth Avenue apartment. It could bring in excess of $35 million on May 6, when it is sold along with three Renoirs and other works. 

In a June 18 sale, William Merritt Chase's painting A Water Fountain in Prospect Park could fetch $1 million, and a gorgeous John Singer Sargent of a Girl Fishing at San Vigilio is expected to exceed $3 million.

Miss Clark spent the last 20 years of her life in a New York hospital. Clark's will settlement establishes a museum foundation in her Santa Barbara mansion, Bellosguardo, which will house her vast doll collection. Part of the auction proceeds will go to a settlement with Clark's nurse and distant relatives.

A feature film of her life could be in the works. Investigative reporter Bill Dedman, who co-wrote Clark's biography "Empty Mansions," has said that producer Ryan Murphy optioned the rights. Murphy is the creator of the TV series “Glee.”