Over the course of 50 years, Jack Naylor has amassed the world's largest private collection of cameras and photographs -- more than 30,000 items in all.

From spy cameras to works by famed Civil War photographer Matthew Brady, Naylor's collection is a comprehensive material history of photography. The self-made millionaire, who built his fortune by inventing an automotive thermostat in the 1960s, houses the massive collection in a climate-controlled basement museum at his home in Massachusetts.

The museum has been open, by appointment, to the public. Now all of it can be yours, for just $20 million -- and Naylor's approval. Why sell? Naylor says his family is not interested in the collection. He wants a buyer who can preserve it as a whole and keep it accessible.

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