Great Diamond Island in Casco Bay is a quiet island community just off the shores of Portland, Maine. The island is often overlooked by travelers who hop off the Casco Bay Lines Ferry for the popular destination of Peaks Island. Great Diamond Island doesn't mind the limited foot traffic, though. The community has long had the reputation of a peaceful, secluded retreat with homes and cottages tucked into private wooded areas and a gated portion of the island protecting the converted historic military structures. For the right price, one of the military buildings turned private homes could be your perfect island retreat.

Most of the old brick buildings on the island have been renovated and turned into condos and single family homes with stunning attention to detail and decor. 181 Diamond Ave on Great Diamond Island is the former pump house of Fort McKinley.

This home boasts four bedrooms, three and a half bathrooms, and over 3600-square feet of living space. The exterior brick is in pristine condition and the tower still stands tall above the building.

The listing says: 

The great room is hallmarked by a commanding fireplace and hearth accompanied by original sliding doors and reproduction tin ceiling. The second level features two suites with full baths and two vanities. The exterior has been meticulously kept and true to history with the original brick stack, a slate roof, expansive patio and mature grounds.

So how much does a converted historic military pump house on one of Casco Bay's most peaceful islands fetch on the market? A cool $795,000. According to the Portland Assessor's office, the structure was last purchased for $47,812 in 1995. That's quite the jump, but can you really put a price on owning a piece of history?