No tenant has been named yet for the empty building on Witherspoon Street that housed the Princeton Army & Navy Store from the 1960s until the store closed early this year. But developer Jeffrey M. Siegel, whose company ML7 Construction & Design owns the building along with the those on either side occupied by Small World Coffee and the accessory store Lisa Jones, has definite plans to reimagine and redesign the long, skinny space.

Mr. Siegel was among three area developers to speak at a breakfast meeting last Thursday at Springdale Golf Club. Organized by the Real Estate Business Alliance of the Princeton Regional Chamber of Commerce, “Revitalizing and Repurposing in the Region” was focused on efforts to revamp and enliven existing buildings that, for various reasons, have outlived their usefulness.

All three of the speakers С Mr. Siegel; James P. Herring, president of Herring Properties; and Jon McConaughy, founder of Brick Farm Group, had examples to share. Mr. Siegel said that Small World Coffee will remain “for a very long time,” and that Lisa Jones has an existing lease. His focus is on redeveloping the former Army & Navy building. “We will design a new entrance to go to the upper floors and pull the storefront out,” he said. “We’ll widen it and create more usable space.”

Mr. Herring focused his talk on a 250,000-square-foot office building in Skillman and a former medical office facility at 281 Witherspoon Street, next to the AvalonBay rental complex that is nearing completion on the site of the former Princeton Hospital. The Witherspoon Street building was gutted and redesigned by architect Joshua Zinder, and is now home to a new combination of tenants.

“The former surgery center on the third floor smelled medical. And it was a rat warren of offices,” Mr. Herring said. “But it had great bones. We re-introduced it to the marketplace by holding an Arts Council event there, which went very well.” The second floor of the building is now headquarters for a law office, financial company, a medical practice, and yoga studio. “Years ago, you wouldn’t see that kind of mix,” he said. “But now, it’s a way of life.”

A second building owned by Herring Properties on the site will be demolished and a new retail building is in development. It will include retail and an eatery on the first floor. “We’re in discussions with a local restauranteur,” Mr. Herring said.

The Skillman complex, located on Orchard Road, was owned for a time by Computer Associates. On a sprawling 70 acre site, it became too large and difficult to lease. “What do you do with a project when it passes middle age?,” Mr. Herring said. “A lot of buildings like this went up between the 1960s and 1980s. This type of corporate campus phase, though, has ebbed and flowed over time. So we’re left with these white elephants.”

Herring bought the complex in 2006 with the intention of making it into Class A office space. New floors, hardscapes, a new entrance, new finishes, and new systems were installed. Energy costs were cut in half. “The biggest challenge is the brokerage community,” Mr. Herring said. “We started to lease space to smaller tenants, and then Johnson & Johnson ended up leasing more.” The company added solar energy and carved off 26 acres for residences, some of which helped Montgomery Township fulfill its affordable housing requirements. “It is almost sold out and rented now,” Mr. Herring said. “It succeeded because we took a white elephant and broke it up into pieces.”

Mr. McConaughy’s Brick Farm Group has developed five businesses over the past 12 years, four of which involved revitalization and adaptive reuse of old buildings in Hopewell. Concerned about producing their own food for their family and, later, their friends, Mr. McConaughy and his wife bought land in 2004 and started Double Brook Farm.

From there came Brick Farm Market, in a former Chevrolet dealership; Brick Farm Tavern, in a building dating from the 1800s; Hopewell Playhouse, built in the 1930’s as a theater; and Brick Farm Creamery. The company turned the town’s former Sunoco station on East Broad Street into renovated office and retail space.

“The whole project has been about food for and by the community,” Mr. McConaughy said. “Animals are born and raised and harvested on the farm. We’ve lost the idea of community along the way. I want my dollars to stay in town. I want to know where my food comes from. So adaptive reuse and history make a place desirable, and that’s what we do.”

The last to speak at the breakfast, Mr. Siegel said his own company “straddles both of their worlds” doing adaptive reuse and traditional suburban office buildings. ML7, which owns approximately $200 million of real estate assets and has offices in Princeton and New York, renovated the old Lahiere’s restaurant now known as Agricola. “We not only make a great building tenants will want, but also buildings that will contribute to the community,” he said.

Mr. Siegel’s presentation included buildings ML7 renovated in the Forrestal Center and in Yardley, Pennsylvania. He is especially proud of The Tannery, a 114-year-old former factory on 10.5 acres that had become “a horrible office complex that paid no attention to its surroundings,” he said. Upon discovering that the building had 30-foot ceilings that had been covered up, Mr. Siegel said he bought it on the spot. Since then, he has made an effort to bring back the building’s original architectural elements, keeping interior details like Pennsylvania stone.

Asked their favorite thing about doing the work they do, the three speakers answered without hesitation. “Looking at a project and imagining what it can be,” Mr. Siegel said. “Confirmation that we’re doing the right thing,” Mr. McConaughy answered. “Every day is a new day,” Mr. Herring said. “That’s what I love about it.”