Construction cranes and pile drivers are again commonplace on Arlington’s residential, commercial and school properties now that the recession’s worst is behind us.

But the downside of progress—the loss of historic character and valued flavor from earlier eras—is worthy of a regular reminder. For that we can count on Preservation Arlington, a volunteer-run virtual network of local heritage activists that keeps a spotlight on threatened buildings that to many are familiar friends.

The website of news, history and annual rankings of most endangered structures is steered by Cherrydale resident Eric Dobson, who combines the nostalgia he injects in the popular Facebook page “I grew up in Arlington, VA” with the detailed research skills he hones on his job with a commercial real estate trade association.

Current offerings on the photo-rich site include results of urban archaeology near the Prospect House condominiums in Rosslyn. They reveal remnants of the old Congressional School and the former home of Gen. George Patton, who was commander at Fort Myer. “These buildings all have stories,” says Dobson. “As a civic leader has said, we can’t have 100-year-old buildings if we keep tearing down the 50-year-old ones.”

This year’s endangered list includes the Key Boulevard Apartments, Arlington Presbyterian Church, general parkland open space, the East Falls Church Commercial Hub, the Wilson School (which Arlington Public Schools is eying for needed space), various examples of mid-century modern architecture and family graveyards in disrepair.

“We do not have formal criteria,” says Dobson, who recently renovated, rather than demolish, his historically registered Sears bungalow at considerable expense. “We send out a request for nominations to our supporters. And our board discusses things throughout the year.”

Colleague Kim O’Connell, a magazine writer and preservation advocate, says, “The list is developed based on thoughtful discussion around a number of factors such as age, architectural style, relevance to Arlington history, rarity, and extent of the threat.” That was also the approach of Preservation Arlington’s predecessor, the Arlington Heritage Alliance.

The current group, rebranded in 2013, partners with the county Historic Preservation Program and the nonprofit Arlington Historical Society on workshops and oral histories, O’Connell notes. Its Facebook group numbers 460.

Arlington’s historical preservation master plan adopted in 2006 acknowledges the county’s “collection of urban villages, offering the convenience of urban living with the human scale of traditional development.” But it also notes that many traditional buildings are “at risk as a result of Arlington’s close-in location to the capital city and high land values.”

Asked to point to signs of Preservation Arlington’s impact, Dobson told me, “I don’t know that we have saved any buildings.” But the volunteers’ efforts helped discussion on the “Blue Goose” property (the doomed Marymount University high-rise at Fairfax Drive and Glebe Road) and “resulted in commitment by the developer to retain and re-use 40 some panels from the building,” Dobson said. The 1913 Fraber House in Cherrydale “has survived thanks to efforts by preservationists keeping their finger on the pulse of the project.”

Compared with Alexandria, “I personally think Arlington is the new kid on the block” in a commitment to preservation, Dobson says. “We are very much focused on the next big thing and are not as focused on our history and the story behind a site, building or community.” Preservation Arlington is “working hard to change that.”