Mr. Dean, whose Georgetown mansion was built in 1826, said he was determined to restore the Kresge home.

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Mystery shopping began in the 1930s with three men touring the country, staking out Woolworth's and Kresge's (now Kmart) department stores.

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He fell for the house itself, too a Mediterranean Revival built in 1937 as the summer home of Sebastian Spering Kresge, founder of the company that later became Kmart.

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Mr. Rush said that the campus's now-closed Kresge museum will move its collection, including 7, 000 objects of Greek and Roman antiquities, Old Master paintings and 20th-century sculpture, into the new space.

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