By E.B. Solomont

When Kansas-born Bill Koch was a newcomer to Cape Cod in the 1970s, he was a frequent guest at the summer home of banking heir Paul Mellon and his wife, the famed gardener Rachel "Bunny" Mellon. After bringing his hosts a couple bottles of wine, Koch would walk through the Osterville, Mass., house with Paul, admiring the couple's enviable art collection.

"He had some of the world's greatest masterpieces," Koch, 85, recalled in an email. "I always wanted a Van Gogh, and he knew it, and would always -- with just a touch of smugness -- steer me into the room where it hung."

Koch never got the Van Gogh, but in 2013 he purchased the Mellons' 26-acre waterfront estate for $19.5 million, property records show. A year later, he bought an adjacent, roughly 10-estate from the du Pont family for an undisclosed sum; he turned that into his primary Cape residence while using the Mellon property for family and guests.

Now, Koch is looking to sell the Mellons' onetime home for $23.85 million. The eight-bedroom waterfront home sits on about 7.5 acres with two two-bedroom cottages, a "beach house," an artist's studio and a greenhouse.

"My main Cape home is next door -- it is plenty big for my friends and family now," said Koch, the founder of Oxbow Carbon, who also has homes in Colorado and Florida. "It is time for someone else to enjoy this marvelous property."

Koch owns more than 32 acres on Cape Cod, and the Mellon property is one of several parcels that he is selling in Oyster Harbors, a gated community on an island accessed by a single drawbridge. In 2023, Koch listed another portion of the former Mellon estate -- roughly 11 acres of land -- for $16 million. Koch is also asking $10.5 million for a roughly 1.75-acre parcel with an approximately 3,700-square-foot house and dock.

Koch, a wine and art collector, is also selling some 7,800 bottles of wine at Christie's in a three-day auction starting June 12, according to the auction house.

Bunny Mellon was known for her landscaping and for her understated sense of style. She designed the White House Rose Garden for her friend Jacqueline Kennedy, who visited the Mellon estate on the Cape.

The Mellons built the roughly 7,300-square-foot Osterville house in 1954. Outside, Bunny had land cleared for a tennis court, fruit trees and flower and vegetable gardens. She kept gardeners busy by instructing them to plant thousands of annuals each year, according to the 2017 book "Bunny Mellon: The Life of an American Style Legend."

The property originally had no sand dunes, so the Mellons had 2,000 tons of soft white sand trucked in and built a 20-foot-high dune between the house and Nantucket Sound. "The newspapers had a field day describing the Mellons' extravagance," the book said.

Paul Mellon died in 1999, and Bunny sold the property to Koch a year before her death.

Koch, who became enamored of Cape Cod while attending the Massachusetts Institute of Technology, had fond memories of the house and his friendship with Paul. Each summer, Paul moved his art collection from Virginia to the Cape. "'My friends,' he called them," Koch said. "He taught me how to live with fine art in a wonderful, intimate way. My neighbors up here can thank him for their views of the Botero bronzes on my lawn."

The main house remains largely as it was when the Mellons built it, including baskets purchased by Bunny. "I wanted to maintain the house as I remembered it," Koch said. "Bunny Mellon's designs and style still permeate the property."

Recently, Koch has rented out the Mellon property for $25,000 a week, according to the listing. An avid sailor who won the America's Cup in 1992, Koch also owns Osterville's Nauticus Marina.

In addition to his property on the Cape, Koch owns a compound in Palm Beach, Fla., and a ranch in Paonia, Colo., with a faux-Western town. He owns an estate near Aspen, Colo., that is on the market for $125 million.

Koch's father founded Koch Industries, a crude-oil-gathering and refinery business. In the 1980s Bill sold his interest in the company and founded Oxbow Carbon, a dealer of ingredients that can be used as fuel or in the production of aluminum, steel and plastic. Koch Industries is now headed by his brother Charles Koch.

Overall, the luxury market in Cape Cod has softened due to economic uncertainty, said Zenas Crocker of LandVest, an affiliate of Christie's International Real Estate, who is marketing the former Mellon home with colleague and Kelly Crosby. "Great properties still sell quickly," he said. Others may take a while or need price adjustments.

The Northeast has seen a cold and rainy spring, which has slowed things further. "It's not like, 'It's May 15, let's go to the Cape,'" he said. "It's 42 degrees and raining sideways."

Robert Kinlin of Berkshire Hathaway HomeServices Robert Paul Properties has the listing for the $10.5 million property.

(END) Dow Jones Newswires

The company founded by Bill Koch's father is now called Koch. "Billionaire Bill Koch Lists Bunny Mellon's Former Cape Cod Home for $23.85 Million" at 3:39 p.m. ET referred to it by its former name, Koch Industries.

(END) Dow Jones Newswires

June 11, 2025 11:40 ET (15:40 GMT)

Copyright (c) 2025 Dow Jones & Company, Inc.