A Georgia philanthropic couple is selling a multimillion-dollar Hall County mansion built near Lake Lanier in 2003 but never occupied.

George and Mary Susan Donovan, supporters of educational institutions, including Georgia Tech and Emory, built the 24,100-square-foot home in Gainesville as a primary residence but no longer plan to live in it, according listing agent Seema Jain of Sugarloaf Realty Partners. The property has attracted the attention of movie studios shooting films in metro Atlanta.

Jain said the Donovans built the home to accommodate grandchildren and great-grands, but their own children have moved away and the home is no longer needed. “The reason for why they built it is no longer there,” the agent said.

Built 10 years ago for $17.5 million, the home has been up for sale several times since 2010, according to Zillow.com. The listing price has gone from $14.5 million in May 2010 to $8.5 million in February 2012. The bidding at the June 24-26 auction will begin at $1.5 million, according to Auction.com

The 13-acre estate includes a guest house, tennis courts, a four-car garage with an apartment and two docks. It has six bedrooms and nine bathrooms, a gourmet kitchen and four-level elevator.

Jain said the home has a steel frame and is built with limestone, stone and brick. “The Donovan family designed this home to stand the test of time, with castle-like construction quality and a combination of classic and modern design features,” the agent said.

Over the years, the Donovans have also turned down offers to rent the property out for tens of thousands of dollars, including offers by movie production companies, the agent said. In March, Warner Bros. expressed interest in renting the home for actors Drew Barrymore, Adam Sandler or directors during filming of the movie “Blended,” which is being shot at Lake Lanier this summer.

Other homes nearby are not as big, or pricey. Several homes near the Donovan property on Serene Shores Drive are valued between $400,000 and $600,000, according to Zillow.

Bidders in this month’s auction must provide a $10,000 deposit and proof of funds. Three open houses are scheduled: 11 a.m.-5 p.m. Saturday, 1-5 p.m. Sunday, and 11 a.m.-5 p.m. on June 15.