The 32-acre summit of King Mountain, fenced off and padlocked for decades just blocks from downtown Larkspur, will become public open space after the Marin County Open Space District Board approved a conservation deal on July 14.

The vote clears the way for hikers to reach the ridgetop's 360-degree views of Mount Tamalpais, the Tiburon Peninsula, and San Pablo Bay. A previous owner had won approvals to build a 27,500-square-foot glass-walled estate on the summit. Instead, the 161-acre property will nearly triple the King Mountain Open Space Preserve, expanding it from 108 acres to roughly 269 acres.

No public money is involved. The Shelby Cullom Davis Charitable Fund, a Delaware-based philanthropy, is covering the entire purchase price and donating a $2 million stewardship endowment to fund at least a decade of trail improvements, signage, and invasive species management. The purchase price was not disclosed, though the property had been listed for $19 million by its previous owner, Omega Three Trust.

"This really came out of nowhere. Nobody was expecting this," said Chris Chamberlain, Marin County Parks director. "It's been a frenzy to facilitate this transaction."

The deal traces back roughly six months, when the Shelby Cullom Davis Charitable Fund cold-emailed Bill Long, chair of the volunteer-led Marin Open Space Trust. Long, who helped create the Marin County Parks and Open Space District in 1972, said such inquiries rarely pan out. But by April, MOST had signed a purchase agreement with Omega Three Trust.

MOST will complete the land purchase and transfer the property to the Open Space District no later than September 8. Opening the summit to hikers could be as simple as unlocking the iron gate blocking the fire road that already connects the existing loop trail to the mountaintop, county officials told the San Francisco Chronicle.

The existing loop trail, open since the 1990s under a public easement, circles the mountain's midsection. But the summit itself has remained private. David Moller, president of the King Mountain Open Space Association, a neighborhood group formed in the 1980s to advocate for conservation, said the group's attempts to persuade former owners to sell never gained traction.

A county staff report noted that acquisition of the property had historically been financially infeasible.

King Mountain is an oak- and redwood-studded knoll visible to westbound drivers on the Richmond-San Rafael Bridge. The summit features native prairie habitat and hardwood forests. Supervisor Brian Colbert, who represents Central Marin, called the deal an important investment in both conservation and community access.

Long put it more simply: "A lot of people have wanted to see this property opened for a long time. This is going to become a really popular destination."