Location: Anacortes, Washington 
Purchased: $13.2 million*
Current Value: $8 million*

Billionaire Paul Allen bought Allan Island, a 292-acre island located off the coast of Anacortes, Washington. Allan Island was named in 1841 in honor of Lt. William Henry Allen, who was killed during the War of 1812. The Microsoft billionaire bought Allan Island in 1992.

The expansive stretch of property has been placed on and off the market, and it needs a lot of renovations and improvements. Most recently, a new dock was completed on Allan Island, and new cabins are also being proposed. Though Allan Island has an airstrip, it is mostly covered in forested, undeveloped terrain.