Buffalo, N.Y. ? Here’s how you find what might be one of the nation’s most important and most unknown historical sites:

Walk into the Light of the World Missions of the El-Bethel Assembly, which since the car wash and the rooming house shut down is the only working concern on a huge city block in a nearly abandoned corner of Buffalo. Enter the bathroom. Remove the blue curtain opposite the commode. Stick your head into a dark hidden shaft.

More than a century ago, there was a false wall there, not a curtain. The shaft led beneath a stairway on the north side of the building to a small cavity. The floor is still dirt, the brick walls still exposed. And here, in a tiny recess, part of the American story of freedom was written.

This cavity has long been believed to have been the last stop on the Underground Railroad, the final hiding place for runaway slaves on their journey from bondage in the American South to freedom in Canada. From here these slaves traveled, under blankets or in disguise, across the Niagara River or Lake Erie.

Today the stories of the Underground Railroad and the stations along its route are being reclaimed by the hundreds, here in New York state and across the country. It is a historical excavation of a different kind, for many of the sites have been abandoned or restored and, because the entire enterprise was conducted in secrecy, records are few. But this is not in dispute: Between the 1830s and the early 1860s, thousands of blacks made their way along a route that was a railroad only in metaphor.

Right now William Henderson, who heads the mission on Michigan Avenue, is engaged in a project to raise awareness and money. He wants to preserve the cavity in the church and to tell the story of the men and women who escaped and of those who helped them along the way. “This place has been left idle,” he says. “People here in Buffalo even the black community here don’t know what we have here. We have to save it.”

Saving it will cost upward of $1.2 million. That includes the price for stabilizing the structure, repairing the hand-hewn beams with wooden pins and patching the brickwork (the founding pastor of the church was a brick mason, but not a miracle worker). Henderson wants to remove the bathroom, open up the space, install good lighting and displays, and add artwork and artifacts. A rich history sometimes requires rich benefactors.

In truth, Buffalo today is a city with few rich benefactors but very anxious race relations. Just this summer, Margaret M. Sullivan, the editor of The Buffalo News, called for a community-wide discussion on racial issues. But whatever the situation here today, it is clear that this city holds a rich vein of black history.

The Michigan Avenue Baptist Church was built in 1845 by black congregants. One of the most active members of the church was Mary Burnette Talbert, a pioneering woman of brave spirit and far vision who helped found the Niagara Movement, forerunner of the National Association for the Advancement of Colored People. Mrs. Talbert’s home was two doors down Michigan Avenue.

Blacks first settled here as early as the 1790s, and a city directory published in 1838 noted the presence of a “colored Baptist and (a) colored Methodist society.” Blacks drove mules on the canal towpaths and worked as chefs, bellmen and waiters at the Genesee and Iroquois hotels all jobs where they became familiar with travel patterns in the region, an incalculable asset once the Underground Railroad went into operation.

The great impetus for the Underground Railroad was the Fugitive Slave Act, which required that runaway slaves be returned to their owners. That law, part of the Compromise of 1850, was signed by President Millard Fillmore a Buffalo lawyer who won a seat in Congress from this area.

An 1842 Canadian law made it clear that slaves who crossed the border had crossed into freedom. As a result, many of the escaped slaves found haven in the southern Ontario community of St. Catharines, where Harriet Tubman herself once lived. But the passage to freedom was not easy, not only because the Niagara River is one of the most treacherous waterways in North America.

“The dangers involved in fleeing, in exodus, were real; the consequences of capture, cruel and immediate,” said a Canadian government study on the Underground Railroad. “But unjust imprisonment as chattel slaves necessitated a belief in a better world, in a world of deliverance from evil. And so they ran.”

They ran, and now time is nearly running out. In Cincinnati, the National Underground Railroad Freedom Center, which is to open its 158,000-square-foot facility in two years on the northern bank of the Ohio River, is scrambling to save artifacts from the freedom flights. The National Park Service has determined to redouble its efforts to preserve Underground Railroad sites, calling the effort part of a “new wave” of parks. And here in Buffalo, behind a blue curtain, is a reminder that the next generation can rediscover history only if this generation doesn’t lose it.

David Shribman is a columnist for The Boston Globe.