Unprecedented underground mapping technology has revealed that Stonehenge did not always stand alone, researchers announced Wednesday.

A digital mapping project uncovered a host of previously unknown monuments surrounding Stonehenge, including burial mounds, massive pits and various shrines. The findings have revolutionized the way archaeologists view the iconic landmark, which was previously thought to be an isolated structure.

"Stonehenge may never be the same again", Vince Gaffney, the project's lead researcher said in a statement. "This project has revealed that the area around Stonehenge is teeming with previously unseen archaeology."

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The survey was completed as part of the Stonehenge Hidden Landscapes Project, a collaboration between the University of Birmingham and the Ludwig Boltzmann Institute for Archaeological Prospection and Virtual Archaeology.

Newly discovered monuments.

Over the course of four years, researchers used remote sensing techniques and geophysical surveys to collect data from the 12-square-kilometer area surrounding Stonehenge. Up to 17 structures were unexpectedly discovered in close proximity to the stone monument.

Gaffney said before this project, the closest known structure to Stonehenge was more than 1.5 miles away. Some of the recently discovered structures are as close as 150 feet from Stonehenge.

"We can interpret the structures in a sense as small shrines or chapels — Stonehenge being like the cathedral, in relative terms," Gaffney told Mashable. "Suddenly, we are looking at a landscape with lots of small shrines, suggesting the area was full of activity, and Stonehenge becomes a different monument."

The researchers believe the new findings are related to rituals and processional routes that culminated at the main structure of Stonehenge. Dozens of burial mounds in the area were also mapped in meticulous detail. One mound discovered was identified as a long barrow, a massive timber building used as a center for elaborate burial rituals that involved exposure and the removal of flesh and organs.

A long barrow burial mound like the one discovered near Stonehenge. Image: Stonehenge Hidden Landscapes Project

The announcement of the project's findings comes weeks after researchers unexpectedly discovered Stonehenge was originally a completely circular structure, underscoring the unknown nature of one of the world's most famous landscapes.

"Despite Stonehenge being the most iconic of all prehistoric monuments and occupying one of the richest archaeological landscapes in the world, much of this landscape in effect remains terra incognita," Gaffney said in a statement.

Wolfgang Neubauer, director of the Ludwig Boltzmann Institute, said although Stonehenge has been widely researched, a discovery of this scale was not possible until now.

"After centuries of research, the analysis of all mapped features makes it possible, for the first time, to reconstruct the development of Stonehenge and its landscape through time," he said in a statement.

The researchers were able to uncover 17 previously unknown ancient monuments Image: Stonehenge Hidden Landscapes Project

The massive discovery is just the beginning, Gaffney said, adding that the vast majority of the information collected has yet to be analyzed.

"What you’re hearing about is simply a mere little finger of the amount of data that we have now," he told Mashable. "We think we’ve got at least another year’s work on this."

Researchers say the analysis will paint a better picture of the ways Stonehenge has changed over time. The consortium ultimately plans to publish a complete atlas of the information they have gathered in coming years.