Google Earth has unlocked the gates to ancient mysteries around the world.

For years, amateur and professional archaeologists have used the search engine’s satellite imagery to discover mysterious earthworks in Kazakhstan, Roman ruins, a forgotten fortress in Afghanistan and more. In the past decade, Google Earth also has helped identify thousands of burial sites and other “works of the old men,” as they’re called, scattered across Saudi Arabia.

Now, archaeologists have uncovered nearly 400 previously undocumented stone structures they call “gates” in the Arabian desert that they believe may have been built by nomadic tribes thousands of years ago.

“We tend to think of Saudi Arabia as desert, but in practice there’s a huge archaeological treasure trove out there and it needs to be identified and mapped,” said David Kennedy, an archaeologist at the University of Western Australia and author of a paper set to appear in the November issue of the journal Arabian Archaeology and Epigraphy.

“You can’t see them very well from the ground level, but once you get up a few hundred feet, or with a satellite even higher, they stand out beautifully.”