Some billionaires make their own collections available to the interested, such as home building and insurance tycoon Eli Broad 's Broad Art Foundation in Santa Monica, Calif.

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For example, he cited a 13th-century crucifixion triptych from the collection sharing the same exhibition space with Damien Hirst's "The Kingdom of the Father, " a three-panel work of mounted butterflies loaned by the Broad Art Foundation in Santa Monica.

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The couple is building The Broad, a new contemporary art museum and worldwide headquarters for their foundation, to open in Los Angeles in early 2014.

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