In 2009, Olga and Michael Kagan were grappling with two major -- albeit unrelated -- life events. They were about to become empty-nesters, and the country was in the depths of the financial crisis.

Seeing an opportunity, Michael recalled the adage to buy "when there is blood in the streets." The couple began hunting for land in Pound Ridge, N.Y., the Westchester County suburb about 50 miles north of Manhattan where they had lived for decades.

The Kagans paid $1.75 million for a roughly 33-acre property with a circa-1950s home. After selling the home and the 3.52 acres it sat on, they donated 10 acres for conservation and retained about 19.5 acres, where they built a contemporary home with a mirror-like facade and glass bridge.

"It was definitely a vanity project, I admit it," said Michael, a mutual-fund manager, explaining why they donated a chunk of land. Olga is a movie producer. "We wanted to create a piece of art."

Now living primarily in Miami, where they own an apartment, the Kagans are listing the roughly 4,500-square-foot, four-bedroom house for $15 million.

Architecture enthusiasts, the couple were inspired by a design they saw in an architecture book. "We wanted to be involved up to our elbows," Michael said.

Completed around 2014, the house was built around the natural topography of the property, including large trees and boulders. "No blasting needed to be done," Michael said. The site dictated the shape of the home, which is separated into two distinct parts -- one with bedrooms and the other with common rooms -- connected by a glass bridge.

The mirrored siding was added late in the design process, Michael said, and is made up of brushed stainless steel, polished stainless steel and a lead-coated copper flashing. "The idea is, as you walk around the house, you get a dappled look that is changing with every step you take, " he said.

The house has a home theater and a floating staircase, with a curved, brass banister. "It looks like ribbon coming down," Olga said. The house also has built-in furniture and custom pieces, including a dining table, which can be purchased separately.

The Kagans, who have two adult children, are making Miami their main residence because they don't like New York winters, and "especially don't like paying New York taxes," said Michael. "It hurts because we love this place."

However, he acknowledged surging property values in both Pound Ridge and Westchester County. "If you're ever going to sell a place like this, now would be the time to do it," he said.

Pound Ridge is known for contemporary architecture, and demand for luxury homes in the area is extremely strong, said listing agent Brian Milton of Compass. The town's median sale price was $1.8 million for the three months ending in May, up 37% year-over-year, according to real-estate brokerage Redfin.

The size of the Kagan property far exceeds the typical 3- to 4-acre envelope in Pound Ridge, and the house would be costly to replicate, Milton said.