Among the discoveries announced Wednesday are 17 ritual monuments, including the remains of a massive "house of the dead," hundreds of burial mounds, and evidence of a possible processional route around Stonehenge itself.

There's also evidence of a nearby mile-long "superhenge" at Durrington Walls that was once flanked by as many as 60 gigantic stone or timber columns, some of which may still lie under the soil.

The discoveries result from the Stonehenge Hidden Landscape Project, a four-year effort to create a high-resolution, 3-D underground map of the landscape surrounding Stonehenge.

The project team, led by researchers from the U.K.'s University of Birmingham and Austria's Ludwig Boltzmann Institute, mapped the area down to a depth of about ten feet