As the place is being cleaned out, in the window of 227 Duffield Street is a sticker that reads “Take It Back Before It's Gone.” That's exactly what members of the Circle for Justice Innovations are trying to do: save this building before it's demolished.

They say it was a stop on the Underground Railroad, the network of secret safe houses for slaves escaping from the South before the Civil War.

"It's a very strong history of this region and this particular street and this particular home that has to be preserved," says Aleah Bacquie Vaughn, the executive director of the Circle for Justice Innovations.

The building dates to 1848 and was owned by famed abolitionists Thomas and Harriet Truesdell. Advocates believe other homes on the block part of the Underground Railroad. They, however, were demolished after Downtown Brooklyn was rezoned in 2004. High rises, including hotels, now stand in their place. The street was co-named Abolitionist Place, but activists say it's not enough.

They've launched an online petition, appealed to the city Landmarks Preservation Commission, and are preparing to go to court this month to save the structure.

"It would be a phenomenal thing for the city and for Brooklynites in particular to be able to come and see the home of abolitionists and see a tunnel where people used to be hidden in safety so they could get to freedom," said Vaughn.

NY1 went underground 15 years ago to see tunnel spaces beneath 227 Duffield when the house was owned by activist Joy Chatel. She blocked the city from taking her property through eminent domain to create Willoughby Square Park. She hoped to turn the space into a museum, but she died in 2014. City Councilman Stephen Levin says while the area had a hand in the abolitionist movement, including Henry Ward Beecher serving as pastor of Plymouth Church, more research into 227 Duffield is needed.

"Now we don't really know whether it was part of the Underground Railroad because the Underground Railroad was very much kept secret," Levin said.

There are also questions about whether the building has been altered too much to be landmarked.  The commission says it has begun a review to determine if it should be saved.