Construction of the new Marin General Hospital, dubbed MGH 2.0, just got a $21 million shot in the arm — the largest gift commitment in the hospital’s history.

The donation from Marin General Hospital Foundation board member Bruce Braden, an oil and gas entrepreneur, was announced at the July 19 topping-off ceremony. It’s a long ironwork tradition to commemorate the placing of the last beam in a project.

Groundbreaking took place in July 2016 on phase 1 of the new $535 million Greenbrae hospital, which will feature two, 4-story towers with 260,000 square feet of space and 114 private beds.

The foundation has raised more than $64.2 million from community members, physicians and staff, according to a statement. The campaign has secured two eight-figure pledges and 17 seven-figure commitments, including the five largest commitments in the history of Marin General Hospital.

“Marin General Hospital Foundation is thrilled by the extraordinary support and generosity of our friends and neighbors in Marin County. With the help of these donors, and through our Building Better Health campaign, we’re determined to see that MGH 2.0 exceeds the needs of our community and that our caregivers continue to deliver the highest quality care in the North Bay,” said Andrea Schultz, Marin General Hospital Foundation board chairwoman.

Campaign co-chairmen are Mike Stone, president and CEO of Mollie Stone’s Markets, and technology consultant Joe Abrams, co-founder of Intermix and Software Toolworks.

In November 2013, Marin voters approved a $394 million general-obligation-bond measure to cover part of the cost of the new hospital. The foundation is appealing to the broader community to contribute.

The hospital is expected to be completed in 2020 and will house critical services including the emergency room, operating rooms and intensive care unit. A new parking structure has already been completed.

Phase 2 of the expansion will include a 5-story, 100,000-square-foot ambulatory services building and another parking structure. The start date of that phase is still undetermined.

With floor-to-ceiling windows, green spaces, private rooms, and integrative services, the forthcoming half-billion-dollar facility was designed with patient and staff comfort levels as one of its priorities, plus use of materials, construction process and design to meet high environmental standards.