Mitchell Rales is a billionaire executive, philanthropist and art collector whose primary residence is a 125-acre estate in Potomac, Md., near Washington, D.C. He also owns homes in New York City and near Vail, Colo. Rales founded a company, which turned into Danaher, whose products are concentrated in the fields of design, manufacture, and marketing of industrial and consumer products. His brother, Steven, another multi-billionaire, is the Chairman and CEO. In 2013, his net worth was reported at $3.9 billion. This home is believed to be the most expensive in the state of Maine.