Engineer Lin Deng was wowed by the design of a circular-shaped home he saw for sale on the Internet.

"It looked amazing," he recalled. "I had to see it."

Deng toured the one-level, 7,000-square-foot structure near Northfield and marveled at the 360-degree views of a wildlife preserve area and nearby Circle Lake.

"It's an engineering masterpiece structurally, architecturally and mechanically," he said. In 2010, Deng bought the bank-owned property for a bargain-basement $300,000 and moved in with his wife and two children.

"Many people were scared by the size of the house and the utility bill," said real estate agent Faye Merritt of Re/Max Advisors. "He took a risk."

The first owner, Jim Cook, a precious-metals dealer, hired a Swiss architectural firm in 1981 to design a round home on 200-plus acres of land he owned.

He couldn't keep up with the high maintenance and heating bills for the home, which reportedly cost $2.4 million to build. The property went into foreclosure and was sold at auction in 1992. A former owner installed a geothermal system to make heating the home more affordable.

Deng may have gotten a good deal, but he immediately invested in improvements such as a new septic system, repaired the geothermal system pump, painted the interior and exterior and even replaced the liner in the swimming pool.

But he said he's glad he did because of the home's many one-of-a-kind features.

"The entire roof is a deck," said Deng. His family would often climb the spiral stairs to the roof to watch birds and wildlife. There's also an enclosed wet bar up there.

His wife planted tomatoes and cucumbers in a 32-foot atrium that houses an indoor garden under a massive skylight. "It's like a greenhouse, and part of the beauty of the house," said Deng.

In wintertime, he appreciates the underground heated garage that can hold up to eight cars. "My kids love riding their bikes in there," he said.

Deng recently relocated to the East Coast for a job and has put the circle house on the market. He said his kids will miss the fishing pier, and he and his wife are aware that they will never be able to replicate the home's unique connection to the outdoors.

"The view is everywhere. You can see the stars and moon in the skylight," he said. "It really feels like you are part of nature."

Other features:

• The circular-shaped home features four bedrooms and five bathrooms.

• Most furniture is built in, including an office desk, cabinets and beds.

• The kitchen has marble countertops, a multi-functional cooktop, wood floor and wood-burning fireplace.

• Sauna in the master bathroom.

• Fitness room with floor-to-ceiling mirrors.

• A concrete "safe room" with walls 2 feet thick.

• Geothermal heating and cooling system with an average electric bill of $296 a month.

• Walk-in wine cellar.

• Heated in-ground swimming pool.

• Sits on five acres surrounded by a wildlife preserve.

Faye Merritt of Re/Max Advisors has the listing, www.faye-merritt.com, 507-301-6770.