Subway construction workers in San Francisco are becoming accustomed to working alongside archaeologists as they dig up layers of the city's past to make way for the $1.6 billion light rail line set to connect Chinatown with South of Market by 2019.

And now those teams have unearthed bits of industrial sewing machines dating back to the 1800s at the Stockton Street site, suggesting a sewing factory may have once occupied the land where the Chinese Americans Citizens Alliance now sits, reports the New Historian.

And while rusty sewing machines may not sound sexy, Adrian Praetzellis of the Anthropological Studies Center at Sonoma State University calls the find "unprecedented," saying these pieces could be our only clues to life in that specific area more than a century ago.

The university is among half a dozen archaeological consultants working at the city's many construction sites, and Dana Shew, an oral historian and archaeologist at Sonoma State, will now study the merchant file for the site’s former address, 1018 Stockton St., to try to scare up the names of those who once used the machines.

Found 8 feet below street level, the current hypothesis is that the machines were in the basement of a Chinatown factory that was likely felled by the 1906 earthquake or the ensuing fire that leveled much of the area, reports the San Francisco Examiner.

"There’s very little that remains of Chinatown prior to the [1906] earthquake, so this is basically the last remains of the earliest Chinatown," says Praetzellis. (Archaeologists recently made a bloody find tied to Julius Caesar.)

This article originally appeared on Newser: Archaeologists Find Pieces of SF Before the Quake

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