Deep beneath the busy city streets of the Greek city of Thessaloniki, the ancient world has once again resurfaced as a subway project has revealed numerous artifacts in what was once a thriving trade hub over the course of 2,300 years.

With ongoing work on the subway of Thessaloniki scheduled to run until 2020, the past 15 years of renovation has uncovered extraordinary details about the lives of those who once lived in this busy metropolis, as Phys.org reported.

One of the latest discoveries that archaeologists have made is a major highway that dates back to the 6th century that would have run through Thessaloniki, along with other large scale renovations that were conducted at the time.

As the city’s culture ministry’s Polyxene Adam-Velen explained, before this find was unearthed, archaeologists were unaware that such enormous changes of this kind had been made to Thessaloniki.

“We did not know such important urban changes had been carried out in this era, probably under Byzantine Emperor Justinian. We were surprised to discover the road in such exceptional condition. This phase of the city’s history was mostly unknown to us.”

Also found in the ancient Greek city was a large villa that contained a hot bath. In the area of the hot bath, a gold ring was retrieved that dates back to the 4th century CE, and archaeologists surmise that it was probably dropped accidentally by a woman heading to the bath who was never able to discover the exact location of her lost ring.

Another curious object that was found near the villa were the remains of the head of a bearded man made out of clay that researchers believe was “probably a votive offering.”

The city of Thessaloniki was originally founded during the 4th century BCE and was officially christened with the name of Alexander the Great’s beloved sister. It was a crucial location in the Roman Empire and after the Byzantine Empire took control, it became its second official city.

As history continued and shifted to the Ottoman Empire, Thessaloniki eventually became a haven for numerous Jewish individuals who were cast out of Spain and had nowhere else to go during the 15th century.

Owing to the great amount of history lived through in this city, it should come as no surprise that archaeologists have found a treasure trove of around 300,000 artifacts so far, which include coins that total 50,000 in number. Two marble plazas, an ancient church of the Christian faith still in its infancy, and a massive fountain measuring 50 feet have also been found by archaeologists.

According to Polyxene Adam-Velen, one of the most recent discoveries that thoroughly astounded archaeologists was an area that was used exclusively to manufacture jewelry.

“We found vessels shaped like hand grenades. Initially we couldn’t figure out their purpose. Then we realized they were used to store mercury for the making of jewelry. This plain object was extremely valuable to us. Because ultimately it gave us the interpretation that it was used in these workshops.”

With two more years left to continue with construction of the Thessaloniki Metro subway, archaeologists will almost certainly have many more exciting discoveries left to report.