Scientists have discovered the remains of 90 standing stones buried and preserved under a grassy bank just two miles from Stonehenge.

The monolithic arrangement once formed part of a C-shaped ridge centering on a downward slope in land that might have been used in various ancient rituals. Using ground-penetrating radar and remote-sensing technologies, the archaeologists imaged 30 intact stones measuring up to 4.5 meters tall; the other 60 were fragmented—in total, they faced single-line toward the river Avon. The coolest bit? Taken as a whole, the C-shaped escarpment is five times the diameter of Stonehenge.

“This is archaeology on steroids,” archaeologist Vince Gaffney told the Guardian yesterday. He and his team, all working for the Stonehenge Hidden Landscape project, presented their findings yesterday at the British Science Festival.

The discovery at Durrington Walls—around 4,500 years old—is forcing archaeologists to reevaluate their entire understanding of the area. The stones placed at the Durrington Walls earthworks site could be older than Stonehenge itself, and could help uncover how ancient peoples interacted with the land.