The mercury inside her body is thought have preserved it - allowing experts to determine her connection to one Boris Johnson.
Archaeologists said the woman had been buried in front of the altar and test showed she had been well-fed and wore good quality clothes.
Based on the amount of mercury in her remains she also appears to have been suffering from syphilis, which researchers believe she picked up while caring for others with the sexually transmitted disease.
It turns out the woman is the great-great-great-great-great-great-great grandmother of Mr Johnson who sadly died from mercury poisoning sometime in the 16th Century.
Local historians knew that members of Basel's wealthy families were buried in and around the Barfüsser Church.
The mummy had been uncovered once before - in 1843, during building work at the church.
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It's believed Anna Catharina married a church minister and lived for most of her adult life in Strasbourg, the BBC reports.
Once her identity was established genealogists used the efficient records of births, marriages, and deaths kept by the upper classes to trace more of Anna Catharina's descendants, the aristrocratic von Pfeffels.
Now, after two years of archival and DNA investigation by a team of researchers, she not only has a name - as it turns out, she's also got a rather recognizable great-great-great-great-great-great-grandson.
After the death of her husband, she returned to her home town of Basel, and apparently underwent rigorous mercury treatment in the hope of a cure. The couple's daughter, Yvonne, married Osman Wilfred Johnson Kemal and their son, Stanley Johnson, is Boris Johnson's father.
He once told the BBC genealogy programme Who Do You Think You Are? that he was "the product of many countries", describing his von Pfeffel ancestors as "posh toffs".
The foreign secretary has not yet commented on the discovery, but is known for his worldwide ancestry.