In 1906, Edmund Longyear built a sprawling Dutch Colonial home far from the bustling city — along Upper Lake Minnetonka.

Twenty years later, the country estate became the summer getaway for George Nelson Dayton, his wife, Grace Bliss Dayton, and their five sons. Nelson Dayton, son of George Draper Dayton (founder of Dayton's department store) expanded the 90-acre property and turned it into a working farm with herds of purebred Guernseys and Belgian horses. He named the area Boulder Bridge Farm after the quaint arched stone bridge that spanned the lagoon.

"We heard stories that George Nelson would brag that they were the first to come out to the lake in the spring and the last to leave in the fall," said current owner Tom Wartman, a Lake Minnetonka developer and business owner.

Wartman grew up across the street from Boulder Bridge Farm and, according to his mother, vowed to one day buy the picturesque property on Smithtown Bay. "I don't remember telling her that," he said, "but I did buy it in 1976."

In the early 1980s, he transformed the 90 acres into 44 homesites and walking trails, naming the Shorewood association-maintained community Boulder Bridge Farm, of course.

Wartman and his wife, Rea, raised their three sons on four acres surrounding the gambrel-roofed home, which Wartman had kept for his family.

Over time, the Wartmans updated and improved the century-old Dutch Colonial, making it work for a modern family of five, while preserving its period elegance. Author Bette Hammel gave it a six-page spread in her book "Legendary Homes of Lake Minnetonka."

"Longyear did a beautiful job placing the house on the property," said Tom. "We just did some enhancements."

The Wartmans transformed the original three-room service kitchen into one generous-sized farmhouse-style kitchen with enough prepping, cooking and gathering space for their kids. They blended new cabinets with the original glass-front birch cabinets, refinished the maple floors and created an eating nook. The new boulder-base center island was inspired by the home's fieldstone exterior.

"It's a great space. Tom and I love to cook," said Rea. "And the parties always end up in the kitchen."

The couple also enclosed a three-season porch to create a formal dining room to host their large extended-family holiday dinners. A wall of windows face the vast perennial gardens first cultivated by Grace Dayton.

On the second floor, the Wartmans combined three smaller bedrooms into a luxe master suite with a library and sitting room. On warm nights, Tom and Rea sleep in the glass-walled porch off the master bedroom. "It's like being in my own treehouse," said Rea.

When a storm felled many trees on the lakeside, they filled the open space with a kidney-shaped pool for their teenagers. A large deck area holds a hot tub and outdoor kitchen with a wood-fired pizza oven.

After a century, the inspirational boulder bridge was no longer structurally safe, Tom said. So he preserved its Old World character by erecting a green steel arch bridge between the original boulder piers.

"We've had the honor of being the caretakers for the last four decades," said Tom. "We've tried hard to hold up the integrity and history of the home and surrounding landscape. The gardens that Grace passed down were tremendous."

With their sons out of school and on their own, the couple have decided to sell so they can spend more time traveling and at their home in Hawaii.

"It's a lot of house for just the two of us," said Rea. "It's time for it to be filled with children again."

Other features

• The Dutch Colonial is 8,650 square feet with five bedrooms and seven bathrooms.

• The restored carriage house (1,450 square feet), which has a fireplace and kitchen, and guest quarters above the garage, could be an adjacent residence.

• The home's entertainment area includes a wet bar, movie theater, game room, office and wine cellar.

• The Boulder Bridge Farm community offers biking and walking trails, tennis and volleyball courts, shared lake access and boat slips on Smithtown Bay.

Kevin Sharkey and Tom Wartman Jr. of Better Homes and Gardens Real Estate-All Seasons have the listing, 612-237-7326, www.boulderbridgefarm.com.

Lynn Underwood • 612-673-7619