Sonoma Mountain Estate Sells for Record $38.5 Million

3100 Sonoma Mountain Rd, Sonoma

A huge 1,100-acre estate high on the slopes of Sonoma Mountain has sold for $38.5 million (£29.2 million), setting a record for the highest residential property sale ever recorded in California's Sonoma County. The large agricultural property, known as The Summit and located at 3100 Sonoma Mountain Road, was bought in 2014 by tech entrepreneur Mark Leslie and his wife, Debra Leslie. According to property records and reporting by The Wall Street Journal, the couple paid $12 million for the undeveloped land and later spent another $33 million to redesign, restore and build a highly self-sufficient private estate. The sale broke the previous county record, set in 2023 when an estate in nearby Glen Ellen sold for $35 million.

Transforming raw land into a self-sufficient compound

When the Leslies bought the land in 2014, the mountainous property was mostly undeveloped and needed years of earthworks, infrastructure work and landscape restoration. During their 12 years of ownership, they turned the hilltop into a large private estate, building a modern main house along with guest homes, barns and specialised farming facilities. Official MLS listings (ML82046933) show that the estate has 14,966 square feet of total living space across its buildings. It includes 10 bedrooms, seven full bathrooms and three partial bathrooms. The main house has large open-beam timber ceilings, floor-to-ceiling glass walls and stone fireplaces. Its design takes advantage of uninterrupted 360-degree views stretching from Mount Tamalpais and Mount Diablo across San Pablo Bay to the San Francisco skyline. Beyond the main living areas, the estate has major agricultural facilities, including three modern commercial greenhouses, a 12-car underground display garage and an independent off-grid energy system. The system uses large solar arrays, backup generators and deep freshwater wells.

Extensive ecological restoration on Sonoma Mountain

A large part of the $33 million spent on improvements went towards restoring the natural environment across the 1,100-acre property. To improve natural drainage and reduce erosion on the steep canyon slopes, environmental crews removed invasive vegetation, strengthened natural creek beds and built several private lakes and fillable swimming basins. The project also included planting millions of seasonal daffodils alongside native oak trees, creating open meadows that provide a habitat corridor for local wildlife. The property also has fruit orchards, terraced organic vegetable gardens and dedicated vineyard areas suitable for winemaking. The property's remote location makes it one of the most private estates in Northern California, while still being less than an hour's drive from San Francisco.

A landmark transaction for Northern California real estate

The property was first listed with an asking price of $39.995 million before selling for $38.5 million. MLSListings records show that the sale closed on August 21, with listing agents from Golden Gate Sotheby's International Realty and The Dreyfus Group representing the transaction. "The Summit is a world entirely of its own, offering an unmatched level of privacy, seclusion, and self-sufficiency in one of Northern California's most breathtaking natural settings," the listing agency's marketing material stated. The buyer's identity has not been revealed in public county land records. However, real estate brokers familiar with the deal said wealthy buyers continue to value large and secure properties in coastal California that offer full off-grid independence while remaining close to major technology centres.