With the help of modern technology, the Stonehenge discovery underground exploration gave archaeologists the opportunity to unearth the wreckages of a once-thriving medieval city known as, "Old Sarum."  The researchers also uncovered one of the largest palaces of the historical era.

The Stonehenge discovery underground exploration was conducted by a team of researchers from the University of Southampton. According to The Huffington Post, the archaeologists found the site of the English Heritage, located near the modern city of Salisbury, which resembled two elevated grassy rings with the inner ring once home to a castle.

According to the archaeologists, the Stonehenge discovery underground exploration gave them a glimpse of the life during the historical era though only a few stone walls and some ruins are all that was left. The team also said that they used a ground-penetrating radar that helped them discover massive structures in the outer ring, which were believed to be part of the city's fortifications.

"Archaeologists and historians have known for centuries that there was a medieval city at Old Sarum, but until now there has been no proper plan of the site," University of Southampton's experimental officer and archaeological prospection services director Kristian Strutt said through a news release.

"Our survey shows where individual buildings are located and from this we can piece together a detailed picture of the urban plan within the city walls," Strutt added.

In addition, the team also found locations of individual residential and industrial infrastructures from the settlement's glory days some seven to nine centuries ago, The New York Times reported. They also found furnaces and evidence of quarrying that took place after the city had fallen in the 13^th century. 

The medieval town of Old Sarum, which has become the focus for the archaeological Stonehenge discovery underground exploration, had been cited in some of nation's earliest written annals. In 3000 B.C., the first signs of human habitation was chronicled. Based on history, the site was later used by the Romans, the Saxons and the Normans, who built a trenched castle on a hill and a wall around it.

During the Iron Age, the site was used as a fort, which was approximately oval in shape and was also the site of an early cathedral, built in 1092. While the old one was destroyed in 1219, another cathedral was consecrated on the site of New Sarum or what is known now as the modern city of Salisbury.

In the Stonehenge discovery underground exploration, the researchers used techniques including magnetometry, earth resistance, ground-penetrating radar and electric resistivity tomography that uses electrodes to probe underground.

Next spring, the researchers hope to return to complete the Stonehenge discovery underground exploration of the inner and outer baileys and survey a Romano-British settlement to the south of Old Sarum.