Petra Island, N.Y.
Just when you thought all private islands were covered in coconut groves and soft white beaches (not that we don't love those!), along comes Petra Island, an 11-acre (4.5-hectare) parcel with a big history in Lake Mahopac, N.Y.
There are currently two homes on Petra Island. The smaller of the two is a 1,200-square-foot cottage designed and built by Frank Lloyd Wright in 1950 [source: Private Islands Online]. But the showpiece is a 5,000-square-foot residence built several decades later based on Wright's architectural renderings [source: Colman]. While the larger home wasn't built until long after Wright's death, its design followed his original plan. The result looks very much like a Wright creation and features wide open expanses of stone, concrete and mahogany wood [source: Colman].
Petra Island was on the market as of February 2011, but the asking price wasn't publicly available. Current owner Joseph Masarro bought the island and the cottage in 1991 for a reported $700,000 and completed construction of the main residence in 2007 [source: Mann].