The city of Frederick has paved the way to turn a site representing centuries of U.S. history -- including breeding the horse George Washington rode during the Revolutionary War -- into a potentially massive housing development. At the request of landowner St. John's Literary Institution, the city's Board of Alderman voted to lift "floating" -- or temporary -- zoning for the Prospect Hall estate, reverting it to residential and making it more appealing to a potential developer. The base zoning allows for 12 housing units per acre.

The change affects 30 acres of the estate. The remaining two acres between the main road and the historic home are protected by the Maryland Historic Trust.

But Frederick resident Gary Brooks said he and others are concerned the historic trust's easement isn't enough to stop development from crowding in the home.

"An easement doesn't stop a buyer from going back to the trust to say 'I need to need to cut in a little bit here and a little bit there to make [my plan] work,'" he said. "That's what scares the hell out of me."

The estate's home currently houses St. John's Catholic Prep, which moved there in 1958. The high school is selling the property to help finance a new 49-acre campus on Buckeystown Pike.

Andrew DiPasquale of Miles & Stockbridge PC represented St. John's at the alderman meeting where he said the school is working on settlement of a contract with a prospective purchaser. Neither DiPasquale nor a school administrator returned calls for comment.

The property is steeped in local history. During the Revolutionary War, the owners gave one of their horses, named Blueskin, to Washington to ride in the war. Stephen A. Douglas visited the estate in 1860 while he was running against Abraham Lincoln for president, and in 1863, George Meade took command of the Army of the Potomac in the house's parlor. A year later, the house served as a hospital during the Battle of the Monocacy.

In later years, Prospect Hall was owned by various congressmen and senators and guests included President Truman and Sen. Sam Rayburn.

Brooks, who is a member of Frederick's planning commission but speaking on this issue as a resident, said he hoped a developer would be sensitive to the property's significance.

"My issue is let's ... make sure we're prepared to address the historical issues at hand," he said.