Archaeologists have found that Stonehenge, one of the most famous sites in the world, has a massive stone sibling that is just two miles to the north-east.

Investigators from Birmingham and Bradford Universities and the Ludwig Boltzmann Institute in Vienna have found a 330-metre long line of over 50 huge stones. Stones were found buried under part of the bank of Britain's biggest pre-historic henge.

For the project, investigators used powerful ground-penetrating radar, which can 'X-ray' archaeological sites to a depth of up to four meters.

Co-director of the investigation, Professor Vince Gaffney of Birmingham University, said that they did not have any idea about these stones.

The geophysical evidence shows that each buried stone is about three meters long and 1.5 meters wide. It is placed horizontally in its earthen matrix. It is considered that may be these tones were brought to the site soon before 2500BC.

After looking the stones, it appears as if they have formed the southern arm of a c-shaped ritual 'enclosure' and rest of which was made up of an artificially scarped natural elevation in the ground.

The c-shaped enclosure is over 330 meters wide and over 400 meters long and is faced straight towards the River Avon. Later, the monument was changed from a c-shaped to a roughly circular enclosure. Presently, it is known as Durrington Walls, Britain's largest pre-historic henge. As a religious complex, it would surely have had a deep spiritual and ritual link with the river.

With the help of ground-penetrating radar, magnetometry and other geophysical techniques archaeologists have discovered around 17 other henge such as Neolithic and Bronze Age religious monuments. Each is between 10 and 30 meters in diameter. They have also found around 20 large and enigmatic ritual pits each up to five meters in diameter.

Total about 4.5 square miles of buried landscape has been surveyed by the joint Birmingham/Vienna team, which took four years to complete. Now, the archaeologists plan to study the new data to know that how the newly found prehistoric monuments are connected to each other.