For 1,400 years, an underground burial chamber lay untouched in the British countryside, hiding its long-dead denizen and his royal secrets.

Then, in 2003, construction workers in the town of Prittlewell (about 40 miles from London) were expanding a roadway when they stumbled upon the remarkable tomb. Over time, researchers unearthed a lyre, gold coins, a golden belt buckle, and luxury items like drinking horns and bowls.

Unfortunately, the body of the occupant's body had long dissolved due to the acidic soil in this part of the UK; only tiny fragments of tooth enamel were left behind. The lack of human remains made it almost impossible for researchers to identify who the grave's owner was. But analysis of the other artifacts led archaeologists to believe that a Christian Anglo-Saxon prince had been entombed there.

Now, after more than 15 years of excavation and restoration work, archaeologists from the Museum of London Archaeology (MOLA) have discovered that the tomb may be the site of the earliest Christian royal burial in Britain.

The researchers used radiocarbon dating to determine the age of the gold coins, and extrapolated from there.

"The dating has helped us to clarify who it might or might not be," Sophie Jackson, director of research and engagement at MOLA, told Business Insider. "Initially we thought this could have been King Saebert...but we know that he died in 616, and this man is likely to have been buried in 580s or 590s."

King Saebert is believed to have been the first Saxon king from this part of Europe to convert to Christianity. The MOLA archaeologists now think the tomb belonged to Saebert's younger brother, Seaxa.

Jackson said in press release that the finding could be seen as a British "equivalent to Tutankhamun's tomb," since the splendor of this Anglo-Saxon prince's tomb rivals that of the Egyptian ruler better known as King Tut.

"This is one of the most significant Anglo-Saxon discoveries this country has seen," Jackson said.

Here are 23 images of the archaeologists' impressive findings.