A photo of a red-brick, gabled house in Braddock illustrates one of Jonathon Denson's blog posts, at the bottom of which he wrote, "P.S. I would be very pleased if someone with money stepped in and saved that ridiculously awesome house."
Taxes on the house, at 210 Talbot Ave., have not been paid since 2009, according to the county website. It was built in 1875 and has a gable over the middle of five upper windows and a porch that runs the width of the house.
In the image on the county's website, the hedges are clipped. When Mr. Denson snapped his recent photo, the foliage had grown wild, obscuring a view of the first floor.
It is one of many buildings and neighborhoods Mr. Denson, a Michigan native, champions on his blog, Discovering Historic Pittsburgh at www.jonathondenson.com.
The 27-year-old social worker moved to the city four years ago with no local contacts or a job.
"I went on a road trip after college, and I loved St. Louis," he said, "but then I came east and went through Pittsburgh and I really loved Pittsburgh, the hills and the houses perched on them."
He decided to stay.
He took a job at Walmart before finding a career fit with UPMC as an adviser and therapist for mentally ill patients in long-term care. He discovered Stowe, with its 30-minutes-for-a-nickel parking meters and a tailor who will fix pants for $2, and bought a vacant row house for $11,000.
"When I came to Pittsburgh," he said, "I saw so many great old abandoned buildings, and I thought, 'I think I've got to save these.' "
On a lean budget, his method is a campaign to raise consciousness about the merits of historic architecture -- from the spectacular to the obscure. He has scoured the city and its inner-ring suburbs, carrying his camera and chronicling the built environment.
What makes him unusual is the convergence of his passion with his age. Twenty-somethings are a rare breed in the preservation community. But that may be changing.
Dan Holland was 33 when he founded the Young Preservationists Association 10 years ago and says now that "it was pretty lonely. I thought, 'There's gotta be somebody else my age who cares about this stuff.' "
Mr. Denson loved old architecture but never thought about it as a cause until "I had a friend who was into old stuff," he said, "and somehow I picked up on it. I don't know if maybe you just need for someone to show you."
On a recent ride through Stowe, he pointed at buildings out the car window. "That was the old judge's house. It's vacant now.
"Look, that old house has its original trim."
In Esplen, he pointed to a vacant lot and said, "That's where the old church was," a Presbyterian church from 1892 that he had photographed and posted on his blog before it was razed recently.
Esplen is a city neighborhood shaped like a pork chop bone cupped around Sheraden. "It may not be here in 10 years," he said as the car inched down narrow streets of more blank space than structures. "It's barely here now."
Much more "barely there" is a neighborhood he featured on his blog under the headline "The Remains of Schweizer Loch."
Schweizer Loch was a German-Swiss enclave west of the 16th Street Bridge from the Allegheny River north to East Deutschtown on the North Side. Today, four houses, three on Canal Street, are all that's left of the residential component of the area, now dominated by parking lots.
He posted numerous photos on his blog and wrote, "It is my hope that these photographs will illustrate the importance of preservation, and the fragility of our historic neighborhoods, which can be lost forever."
His blog includes photo tours, information about how to buy abandoned properties, photos of what he calls "Urban Prairie."
Mr. Denson's blog has done a lot to spark the interest of Adam Hurt, a 28-year-old musician in North Carolina who said "moving to Pittsburgh is on my shortlist."
"I became aware of Jon and his interest in preservation through his postings on the Citydata Web forum. He posted some really interesting photo tours of Pittsburgh. Its historic fabric is beyond belief."
Mr. Holland said more people across all age groups are buying the argument that historic buildings enhance the potential of a place, but he was so encouraged by Mr. Denson's efforts as a 20-something with more than 35,000 site views that he said, "It's the best news I've had in a while."