The Whitemarsh Township Board of Supervisors has given a developer the green light to build 67 townhouses on a Plymouth Meeting farm that served as a major stop on the Underground Railroad. But a citizen group that has been fighting to protect two historic buildings on the property is considering an appeal.

The Friends of Abolition Hall have argued that the townhouse project would destroy the integrity of one of Pennsylvania's most significant historic sites. The 10-acre Corson property, at Germantown and Butler Pikes in the village of Plymouth Meeting, was a hotbed of the antislavery movement during the first half of the 19th century. The farm's owner, George Corson, was a committed abolitionist who provided escaping slaves with a safe refuge and turned his barn into a lecture hall for antislavery rallies. Speeches by people such as Frederick Douglass and Lucretia A. Mott attracted so many people that the barn became known as Abolition Hall.

The entire farm, including Abolition Hall and the Corson homestead, was listed on the National Register in 1971. But, two years ago, K. Hovnanian Homes acquired the rights to the property with the aim of developing the open land for townhouses. Although the two historic buildings would be left standing, they would lose their defining landscape. The 67 townhouses would come virtually to their back doors.

The Friends of Abolition Hall have asked the supervisors to require Hovnanian to provide a buffer between the historic buildings and the new development. While their resolution, passed Thursday evening, increases the buffer slightly, it would leave the two buildings with just 1.6 acres between them.

The supervisors imposed a total of 22 conditions on Hovnanian. But Sydelle Zove, who heads the Friends group, said, "We feel it doesn't go far enough. When you boil it down, it essentially says they have to comply with the zoning code."

Numerous groups joined with the Friends of Abolition Hall in asking the township supervisors to reject Hovnanian's development plan. They range from the National Park Service to the Avenging the Ancestors Coalition, a Philadelphia group that lobbies for the protection of African American historic sites. The board also heard from best-selling author and editor the Rev. James J. Martin, who grew up in Plymouth Meeting and serves as a communications consultant to Pope Francis.

"The destruction of this unique and historic landscape is not worth whatever financial gain the township will receive in the long run. History, our shared history, is more important than money," he wrote in a letter to the board.

A Hovnanian spokesman, Brian Dries of Ceisler Media & Issue Advocacy, said the company was gratified by the supervisors' decision: "Hovnanian has reviewed the 22 proposed conditions and finds them acceptable." Hovnanian still needs final approval from Montgomery County and the local historical review board. The Friends of Abolition Hall has 30 days to file an appeal.