Tom Moore and his wife, Avril Barton Moore, both 1973 graduates of Princeton University, bought and renovated the $3 million, 82-acre Tusculum property when they came to Princeton in 1996. Last year they capped off the project with an agreement that preserves the land around the Cherry Hill Road property as open space.

The historic property, adjacent to Mountain Lakes Preserve, had been the summer estate of John Witherspoon, Princeton University’s sixth president and signatory to the Declaration of Independence. Witherspoon, an orator and preacher, built the house in 1773 and named the estate after a home built by another orator, Cicero. Cicero’s Tusculum was built in a resort town that was 15 miles from Rome.

“We wanted to find a house on a small piece of land, easy to keep up, and comparatively modern so we wouldn’t have to pay much in upkeep. We set out our strategy and then did exactly the opposite,” says Moore. Their real estate agent, who was working at the Henderson family’s agency, Rosemary Rogers, had a personal connection to a previous owner of the Tusculum estate and knew it well.

The Moores did not like any of the houses that met the requirements they had laid out. “Finally she said, ‘now that I have gotten to know you I think you are going to love this,’ and she showed us Tusculum. I saw that the land is just so beautiful — but Avril thought I was nuts. The house was falling apart. The floors had fallen through. The rain had gotten into the basement.”

They found an architect who specializes in preservation: T. Jeffrey Clarke is an alumnus of the University of Virginia, Class of 1977, with a master’s degree from the University of Michigan, and he was then president of the Historical Society of Princeton. “There was a great deal of work to restore what was there,” says Clarke, “and the original portion within the stone walls was 800 square feet per floor, remarkably small.”

“In their stewardship of Tusculum,” says Clarke, “Tom and Avril Moore have done an amazing job of preserving this significant historic site, so important to the Princeton community, while developing the property for their own residential use in a manner appropriate to the way that people live today.”

The original stone structure was built in 1773, and a wing was added in the 1830s. Successive occupants — including the Stocktons, the Pardoes, and the Pardees — added two more wings and enlarged it to 5,000 square feet, all in Colonial Revival style. In the 1920s it was used as a hunting lodge.

The Moores’ renovations replaced the 20th century additions and added 6,000 square feet for a total of 8,000 square feet and two dozen rooms.

One example of the expensive changes: The Moores wanted to recreate the “elm allee” that had been there in the 1930s. When the elms died, they were replaced by 20 Norway spruces. The Moores persuaded the township historic preservation committee to let them fell the spruces and plant mature specimens of today’s “elm look-alikes,” Zelkova trees.

The Moores, who have been married for 31 years, lived in town near the Lewis School during the nearly three years needed to restore and enlarge the house and in the restored mansion for six years. Now they have separated. Though Avril and her daughters still live at Tusculum, it is unclear what will happen to the property. But the Moores’ expansive and expensive renovation project culminated in a triumph — they closed a deal to permanently preserve some of the property as open space.

They sold 35 acres to the township for $2.9 million, for just under half its market value. Monies were also contributed by the township, Mercer County, the state Green Acres Program, the Friends of Princeton Open Space and the D&R Greenway Land Trust facilitated the contract. This deal will connect three existing community parks and involves 23 acres of conservation easements. No developer’s bulldozer can intrude on these historic grounds.