A mystery cracks open

Tricia L. Nadolny has an article in The Philadelphia Inquirer about some odd local history:

A public works crew pulling up the sidewalk in the heart of West Chester last week heard an unexpected crack. What the workers uncovered is a mystery that has since perplexed the borough. Beneath the bricks on Church Street, they found a glass manhole cover. And, beneath that opaque window, they looked down on a hidden room. Another layer down, beneath a film of dirt and dust, they saw a metal chair, a few bottles, and an archway long ago closed by concrete.
In West Chester, residents have uncovered tunnels remaining from steel lines that once crisscrossed beneath the borough's two-hundred-year-old streets, according to local historian Jim Jones.
But, unlike those tunnels, this room with its glass window from above serves no clear purpose. And speculation offered by curious residents, who have suggested uses from storage to a hideaway for slaves, has led to little consensus.
"I can tell you exactly what it is," said Jane Dorchester, an architectural historian who lives on Church Street. The curved brick roof gives away the space as a root cellar, she said, adding that it was probably carved out as part of the Mansion House hotel, constructed on that corner by William Everhart in 1832.
Her theory, though, is tested when Jones adds his findings to the mix.
In old maps of the hotel, Jones found that the dining room, not the kitchen, ran along Church Street. The kitchen abutted Market Street, not far from the uncovered cavern, but also not where he would expect a chef to store the vegetables. "If it was something that had to do with a kitchen, it would have been on the Market Street side," Jones said.
It's not uncommon for caverns and tunnels to be found under cities along the East Coast, remnants of a time when it was easier to build down than up, said Don Wildman, who once hosted a History Channel show on the topic: Cities of the Underworld. Wildman, who went to school in Chester County, said spaces were carved out for everything from refrigeration to bypasses that allowed merchants to avoid busy streets above.
Jones wondered if the room might predate the hotel and been connected to a farmhouse that stood near that intersection before Everhart bought the property. Jones and Dorchester both have dismissed the possibility of the room being a hiding spot on the Underground Railroad, pointing out that fugitive slaves avoided West Chester due to its large law enforcement population.
But Malcolm Johnstone, executive director of the West Chester Business Improvement District, wasn't so quick to discredit the theory. Everhart, he said, was a known abolitionist. "The speculation that I've gotten was that it was part of the Underground Railroad. And that's not a stretch," Johnstone said. He conceded, though, that the room appears to have been used for storage, and guessed that it was once filled with bottles of beer and liquor for the Mansion House's tavern, which was accessed on Church Street.
But that possibility, and the other storage uses proposed by Jones and Dorchester, doesn't explain one element of the room: what about the glass manhole cover?
"That's a fine question," Jones said. "I don't know, maybe Martians landed. That makes no sense at all to me. Unless at some point it was used for something where they wanted to let some light in."
The room's purpose and age could be clarified through a review of the glass and hardware on the manhole cover. But West Chester Public Works Director O'B Laing said he has not been approached by anyone with the resources to do that work. Until then, he said, the room will be capped with a concrete slab and preserved for safekeeping.

Rico says a splendid mystery, indeed...