Old stone wall in Santa Clara County, California, courtesy of Wikipedia.
The East Bay Walls, also known as the Berkeley Mystery Walls, are crude walls and rock lines found throughout the hills surrounding the San Francisco Bay Area of California.
These lines of stacked stones, built without mortar, range from a foot to about three feet high and run for hundreds of miles, as far as Chico and Red Bluff, California. Most walls are about three feet wide and run in sections ranging from several feet to over half a mile. The stones used to build the walls range from basketball-sized stones to large sandstone boulders weighing a ton or more. The walls are not all the same—some run in long straight lines, while others form angles, rectangles, or circles. Throughout the area, elongated formations of large stones can be found, some stacked, some not. Sometimes, parts of the wall are carefully constructed, while in other places, it looks like a pile of rocks.
Some are just rows of stones, forming lines that are sometimes spaced. Some have sunk into the earth and are overgrown with vegetation.
In the Oakland hills, the walls head inland towards Mt. Diablo, where stone circles of up to 30 feet in diameter can be seen. In other places, the walls form a 200-foot circle surrounding a large boulder.
The walls’ exact age is unknown. However, some of the first Spanish settlers in the area, as well as the Ohlone Indians, said they were already there when they arrived.
For more than a century, Bay Area residents have wondered who built these walls, how old they are, and what they were used for.
But no one has answered, and their purpose remains unknown.
They are too low to have been used for defense, and the multiple discontiguous sections suggest they were not utilized as fences.
In 1904, Dr. John Fryer, professor of Oriental languages at U.C. Berkeley, declared:
“This is undoubtedly the work of Mongolians… the Chinese would naturally wall themselves in, as they do in all of their towns in China.”
The same year, the San Francisco Chronicle dramatically announced an amazing find unearthed by a University of California chemistry professor named Henry Coffinberry Myers.
“Stone age relics discovered in the Berkeley Hills. A five-faced stone image from a cave, a prehistoric ax, and two pieces of pottery seem to change the accepted history of the western world.”
— San Francisco Chronicle, September 4, 1904
East Bay Walls courtesy San Francisco Chronicle.
The article goes on to say that when Dr. Myers excavated a cave in a cliff, he found a piece of rhyolite stone with five faces carved on its sides… proving that chiseling was done anywhere from 1000 to 10,000 years ago. One face in it has some Indian characteristics; the other four are unmistakably Mongolian. Dr. Myers also found a stone axe, a large flat stone table, a fireplace filled with bones, and an earthenware jug.
The guestimates regarding the building of these walls range from the mundane, such as settlers placing the stones to help guide and corral livestock, to navigational aids utilized by extraterrestrials.
Others theorize that a vanished tribe of “superior” Native Americans, ancient voyagers, or other Indian tribes built the walls for mystical or ceremonial purposes. Some say that the Ohlone Indians built the walls; however, the tribe denies this, and they were hunter-gatherers who were not known to have built permanent structures.
What isn’t explained is how some of the hefty boulders could have been moved, and for what purpose.
No written documentation identifies when they were built, by whom, or why. The oldest published mention of the “mystery” appeared in the San Francisco Chronicle in March 1896.
Stone wall in a San Jose, California park.
Forensic geologist Scott Wolter theorized that the wall is only 200-300 years old based on testing of the limestone. Other tests of the lichen on the stones suggest they were probably built between 1850 and 1880.
Since 2016, archaeologist Jeffrey Fentress has been measuring and mapping the walls, hoping to secure protection from development or other destruction eventually.
The East Bay Walls are accessible in several area parks, including Ed R. Levin County Park in Santa Clara County, the Mission Peak Regional Preserve in Alameda County, and others.
©Kathy Alexander/Legends of America, updated November 2026.
Also See:
Legends, Ghosts, Myths & Mysteries
Sources:
KQED Radio
Mysterious Walls
Relics of the Ancients
Wikipedia