Everyone in the San Francisco Bay Area knows Mt Umunhum, even if they don’t know its name. The large concrete box that sits atop the summit was one the base of a Coastal Defense Radar at the Almaden Air Force Station. Visible from all over the Bay Area, the “Cube” has been a landmark since the base opened in 1958.

This weekend I had the opportunity to visit the closed summit with the Umunhum Conservancy. Not only did I get a close look at the Cube, I got a peek at what is coming when the site opens to the public later this fall. There is still a lot of construction work to do, but the end is in sight!

Ununhum Conservancy Visit to the summit - soon to be public parking
Umunhum Conservancy Visit to the summit – soon to be public parking

Mt Umunhum History

From 1958-1980, over 200 people simultaneously lived and worked around the summit of Mt Umunhum. They performed the critical Cold War mission of carefully watching the radar pings for incoming Soviet bombers. Once missile technology advanced beyond this radar defense system, the base was shut down and eventually became the property of the Midpeninsula Regional Open Space District (Midpen).

Mt Umunhum Radar Tower Base "The Cube"
Mt Umunhum Radar Tower Base “The Cube”

Despite being owned by a publicly funded park district, the land remained closed. The site needed cleanup efforts to remove things like asbestos and lead based paint, and no one wanted to pay. After literally decades of squabbling, the government finally provided remediation to the site and all of the original buildings have now been demolished except the concrete radar tower.

This thing is huuuuuuge
This thing is huuuuuuge

According to many, the tower has historic significance and an effort is underway to save it. To historians it is a reminder of a particular period in US history where we feared nuclear war and spent billions of dollars protecting our West Coast. But to most locals, it is a symbol and a unique feature that defines our skyline as much as any downtown building. However, Midpen leadership hasn’t exactly been supportive of the preservation argument.

Recently, the Santa Clara County Historical Heritage Commission voted to include the Cube on its inventory of historical buildings. While the future of the Cube is still unknown, this creates bigger hurdles for the ‘knock it down’ crowd. Hopefully it will enjoy further protection and funding, so that it can be cleaned up and become the educational resource it should be.

For peakbaggers: the high point is now the dirt pile to the northwest of the cube
For peakbaggers: the high point is now the dirt pile to the northwest of the cube

For more information on the status of the Cube visit the Umunhum Conservancy. These folks are working tirelessly to preserve the tower as well as document the history of the Almaden Air Force Station.

Opening of Mt Umunhum in 2016

The good news for you is that the cleanup of the summit has finally been completed and Midpen is working on improvements for public use. Like Mt Diablo and Mt Tamalpais, the summit will be accessible by car. Normally this wouldn’t be my choice, but since there is a paved road already running to the summit and there is a building there, I think it makes sense. There will be a shaded structure next to the tower for enjoying the eastward facing view.

Midpen is also taking advantage of the accessibility by building an ADA Compliant loop trail around the summit with interpretive signage about the military history, natural features of the mountain, restoration efforts, and Native American history. Mt Umunhum is the site of the creation story for the local Amah Mutsun Tribe and the summit will contain a prayer circle for ceremonies.

For those who prefer to hike or ride instead of drive, a new 4.5 mile multiuse trail is being built to the summit from the current Bald Mountain Trailhead.

The trail winds under the Doppler Station
The trail winds under the Doppler Station

There are no plans to restore the old residential area between Mt Umunhum and Mt Thayer, but the original buildings have been demolished. If you wander the grounds you will still find signs of the small community that lived here for over 20 years. Peeking out from the ground is the tile and edge of the original swimming pool.

Almaden Air Force Station Swimming Pool
Almaden Air Force Station Swimming Pool

Also, keep an eye under your feet. Midpen recycled as much material as possible in the restoration effort. After removing toxic elements like lead based paint, the original structures have been pulverized to use as filler as the land is being evened out and restored. Look under your feet and you may see more than rocks. You’ll see concrete, pressed wood chips, and maybe even little pieces of an old Formica countertop.

Someone's old Formica countertop is now mulch
Someone’s old Formica countertop is now mulch

While the date is not exact, Mt Umunhum’s summit is estimated to open to the public this fall. On a clear day you will get beautiful views of Monterey Bay to the west, and if it’s particularly clear you might even see a peek of the Sierra Nevada to the east. But don’t let a hazy day stop you – come on up and touch the ‘Cube’ and soak in the history of this unique mountain summit.

I touched it! I touched it!
I touched it! I touched it!
  1. Thanks for being with us Rebecca. Great write-up and glad you enjoyed the visit to the summit!

  2. I can’t wait to get up there and see the view. Tried to get in years ago and couldn’t. I’ve been looking at this building on my way home from work, errands, fun stuff for years and it’s my landmark. I particularly like to see it tucked right by the Cambrian Park carousel when I head south and I’m sitting in traffic on Union at Camden. Happy to know these two landmarks might stick around for generations to enjoy.

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