House of the Day

Bill Gibbs started building this house in Scottsdale, Ariz., in the late 1990s. It was completed in 2002. Photo: Baxter Imaging LLC

He says he had previously built an adobe house in the area. 'I would never do that again,' he says. 'Adobe is mud, and it's not a 100-year house like this house is.' Photo: Scott Wang Photography

Mr. Gibbs, the former president of the University of Phoenix, says he spent $12 million on the house, including the land. Photo: Scott Wang Photography

There are two kitchens, five fireplaces and an outdoor firepit. Photo: Scott Wang Photography

The home features Hawaiian Koa wood, as well as honed flagstone. Shown here is a saltwater aquarium. Photo: Scott Wang Photography

Mr. Gibbs's collection of modern and Southwestern art hangs throughout the house. Photo: Scott Wang Photography

In the dining room is an art piece from India, which Mr. Gibbs says he bought at an auction in Los Angeles. Photo: Scott Wang Photography

The roughly 16,000-square-foot home has eight bedrooms. Shown here is the master bedroom. Photo: Scott Wang Photography

There are nine full bathrooms and three half bathrooms. The master bathroom is pictured here. Photo: Scott Wang Photography

The home's notable amenities include an observatory with a retractable roof and dual telescopes. Photo: Scott Wang Photography

There is also a custom-built train for children. An adult operates it from the blue conductor's seat, and the children's seats are behind it. According to the listing, it was modeled on the Santa Fe railway. Though the train was added primarily for Mr. Gibbs's children, he says he has used it at charity events as a bar car. The property also includes a 300-foot zip line, which guests sometimes also used. Photo: Scott Wang Photography

Pictured here is the 4,700-square-foot indoor gymnasium, which includes a weight-training area. There is also a 2,000-square-foot wood-working shop and an eight-car garage. Photo: Scott Wang/Scott Wang Photography

The gym's bathroom is shown here. Photo: Scott Wang/Scott Wang Photography

Shown here is the guest patio. Photo: Scott Wang Photography

A guest bedroom is shown here. Photo: Scott Wang Photography

Mr. Gibbs has three children, who range in age from 16 to 19. Photo: Scott Wang Photography

'It's been a fantastic house for us,' he says. 'It was great when the kids were knee-high, but now that they are 6'2" and going to college, it's a little different. We've had a lot of fun in this house.' Photo: Scott Wang Photography

Mr. Gibbs says his he particularly likes the property's 'serenity.' 'We're out in the high desert of Scottsdale, and we've got a lot of land around us. It's very peaceful.' Shown here is the view from the house. Photo: Scott Wang Photography

Mr. Gibbs says a unique property like this 'would probably take years to sell' using traditional means, so he has decided to try an auction instead. The auction, which is being handled by Grand Estates Auction Company, is scheduled for Feb. 7 and will be absolute, meaning that it will sell regardless of price. Photo: Baxter Imaging LLC