Activist and writer Marie Castle never tired of living in the geodesic dome home she built in 1982 in north Minneapolis.

“The novelty never wears off,” said Castle in 1994, the year her home was featured on the Minneapolis-St. Paul Home Tour. At that time, it was the first and only geodesic-dome house within the city limits. “There’s something really stimulating about it, all the different shapes and angles. Every time I walk in, I feel like it’s an interesting place to live.”

Castle died earlier this year at age 91. “She loved her home,” said her daughter Susan Jackson. “She was a free spirit, and it fit her personality — out of the box and young at heart.”

The dome hit the market this week, priced at $190,000, and quickly attracted 10 offers.

Castle was seeking an unusual house, she said in 1994. “I’ve always been interested in different types of housing, and I was thinking about a log home, an earth-sheltered home, anything but a standard house. I settled on the dome, which arrived from the factory like so many Tinker Toys, which went together pretty easily.”

Serving as general contractor, Castle built the home with her late husband and a friend who lived with them before moving to assisted living. The friend had to use a wheelchair, so the house was built to be handicapped accessible, with wide doorways and other features, said Jackson.

Castle built the dome on a large lot in the Camden neighborhood near Shingle Creek Park. Its private location on a low-traffic street is “a big selling point,” said listing agent Fritz Bredenbeck, Coldwell Banker Burnet.

The site, a dried-up lake bed, had soft soil, said Jackson. “It couldn’t have a basement. It had pilings. A traditional house wouldn’t have worked. This worked beautifully.”

Castle’s dome home was the first in Minneapolis, according to Dennis Odin Johnson, founder/owner of Natural Spaces Domes, North Branch, which supplied the kit for her home. There are now 92 geodesic dome homes in the Twin Cities and about 250 in the greater metro area including western Wisconsin.

Geodesic domes have an aerodynamic shape designed to withstand storms, high winds and earthquakes, and to be energy-efficient. Castle’s home, with its 16-inch walls, was no exception. “She rarely had to turn on her furnace,” said Jackson. “Her gas fireplace provided enough heat.”

Inside, the three-level dome has 1,900 square feet, and three bedrooms, with two on the first floor. A spiral staircase leads to the second level, with a small living and dining area and another bedroom, with a separate entrance and a deck. A pull-down staircase leads to a loft with skylight.

Castle, a former Catholic, became a prominent atheism activist and founder of Atheists for Human Rights. Her home became a gathering spot for non-believers. “She held a lot of activities there,” said Jackson. “She hosted talks and study groups. She had a little library and people would come and read there.”

Castle also was politically active, a charter member of the National Organization for Women when it first organized in Minneapolis, and later served as a delegate to the Democratic National Convention in the 1990s. She was inducted into the DFL Women’s Hall of Fame in 2008.

A prolific writer, Castle earned a degree in journalism in her 40s, while working full-time in a factory and managing her household of five children. She worked as an editor for a country music magazine, as well as in public relations and technical writing, and wrote two books, “Divided We Fall: The Secular vs. the Sacred” and “Culture Wars: The Threat to Your Family and Your Freedom.”

She also wrote her own obituary. “I have enjoyed being one of the luckiest people on Earth,” she wrote. “Fate gave me a 91-year break from otherwise endless oblivion and a life filled with political skulduggery and social activism for the rights of workers, women, gays and anti-war efforts.”

“She was a fighter for all people’s rights to the end,” said Jackson.

Fritz Bredenbeck, 612-865-8012, Coldwell Banker Burnet, has the listing. A purchase agreement is pending.