To the north of Restoration Resources, one of Boston’s largest sellers of architectural salvage, are the South End’s rows of brick town houses. To the south is Roxbury’s more affordable mix of 19th-century styles. Between these neighborhoods, and surrounding Restoration Resources’s storefront on Washington Street, is a ripple in the historic fabric — a liminal space of parking lots, housing developments, and the occasional remnant of a largely bulldozed past.

But inside the business, Restoration Resources is brimming with historic detail: 800 antique doorknobs, 90 light fixtures, 200 doors, and 78 mantels, or maybe 87.

“I just counted everything,’’ Walter Santory, the store’s manager, explained in a voice that could narrate an action movie trailer, though his profession would more likely place him in an episode of “Extreme Makeover: Home Edition.’’

Santory is an architectural salvager, which means he sells pieces of old houses to people who are renovating their homes or collecting tchotchkes. Having spent much of his life collecting the detritus of changing neighborhoods, Santory is blessed with an expert knowledge of architectural history that you can’t get from a PhD program.

Now a resident of Brockton, Santory grew up nearby, on the South End’s Noanet Street, which no longer exists. His childhood street was razed in the late 1950s to make way for the Massachusetts Turnpike. Fleeing the wrecking ball, Santory’s family eventually settled in Mattapan, around the corner from the man many consider the godfather of local architectural salvage: Jorge Epstein.

Epstein was a jeweler by day; by night, he chalked his initials onto pieces of buildings that were slated for demolition. The wrecking crews gave Epstein mantels from the old West End, a Roxbury tavern built in 1675, and stonework from the old South Station. During the 1950s and 1960s, they razed so many buildings that Epstein’s collection filled six storage spaces across the city. He later consolidated his findings in a former bus depot/factory on Blue Hill Avenue.

“He felt you could save everything — ‘Why are they tearing this place down?’ ’’ said Santory, whom Epstein later hired at the encouragement of Epstein’s son, perhaps in a plot to date Santory’s sister. But the real setup was between Jorge Epstein and Walter Santory, who would work together intermittently from 1968 until Epstein’s death in 1998.

By the time Santory came aboard, downtown Boston’s largest urban renewal projects were complete. But to stay in business, Epstein and Santory sought out another form of urban destruction, as there can be no salvage without something to save it from. Ultimately, it was the slower-evolving transformations of Roxbury and Dorchester — Boston’s original suburbs — that kept Epstein and Santory busy for decades.

In 1961 and 1962, following tremendous, federally funded land-clearance projects intended to rid Roxbury and Dorchester of blight and install (unsuccessfully) a network of interstate highways, a Harvard instructor and visiting MIT professor named Sam Bass Warner published two related histories. “Streetcar Suburbs,’’ a hardcover book printed jointly by Harvard and MIT’s publishing houses, dutifully chronicled Boston’s first suburban experiment: the escape of the middle class from the inner city to Roxbury and Dorchester, enabled by the onset of light rail in the late 19th century. “The Discarded Suburbs: Roxbury and North Dorchester, 1800-1950,’’ an impassioned 16-page pamphlet printed by a local nonprofit, described the damage caused by the middle class’s second escape act, this time to a ring of suburbs designed around the automobile.

“Discarded’’ Roxbury and Dorchester became a haven for immigrants: “First came the Germans and the rural Americans, then the Irish,’’ Warner wrote in 1961. By then, a community of 90,000 Jews was on its way out of Roxbury, Dorchester, and Mattapan. A larger community of black migrants from the Caribbean and the American South would take their place in an ornately built environment that had become a revolving door for the city’s poorest citizenry.

With the city’s most financially marginalized residents confined to the oldest, most expensive-to-maintain housing, parts of Roxbury and Dorchester fell into disrepair. And for the salvage company, that meant opportunity.

“Those houses were being abandoned and burned,’’ Santory said.

Santory gutted three-deckers that were worth nothing more than the cost of their back taxes. He collected scraps from Victorian mansions subdivided into boarding houses. He salvaged the odds and ends of shuttered synagogues. Oftentimes, the architectural detail wound up outfitting homes and businesses in Boston’s outer-ring suburbs.

With money to be made, other salvage businesses, known as “salvage banks,’’ opened to take advantage of this excess in supply. One was Olde Bostonian, an architectural salvage company still based in Dorchester, recalled Anthony Greenwood, whose father founded the business in 1980. It complemented a demolition business run by Greenwood’s uncles — a pairing of business models repeated in cities throughout New England.

Today, Boston’s salvage banks remember Epstein as a kind of patron saint.

“He was the pioneer, and people like us just followed,’’ said Bill Raymer, now the owner of Restoration Resources and Santory’s current employer.

But Restoration Resources and Olde Bostonian have both changed their business models in recent years. Olde Bostonian rarely takes on new inventory; they’ve pivoted as more property owners bring in historic detail for restoration rather than removal. And in today’s red-hot real estate market, Santory said, property owners who are transforming their old buildings aren’t salvaging the detailed architectural items like they used to.

“They’re just dumping it now,’’ Santory said. “They don’t have time.’’

More so than in the past, architectural salvage is flowing back into Roxbury and Dorchester as those neighborhoods attract more preservationists, developers, and gentrifiers. Dorchester fixer-uppers are no longer subjects for high-budget cable TV shows — communities of young homeowners now document their salvage-supported efforts on Instagram and personal blogs. Epstein’s former home in Mattapan, built in the 18th century but scheduled for demolition as recently as 2005, will soon house a wellness center and an urban farm.

Certain blocks in Roxbury and Dorchester now serve as perfect A/B tests for architectural salvage’s preservative versus destructive capabilities. As Warner’s “Streetcar Suburbs’’ will attest, 19th century builders regularly reused house designs, meaning that today a home in its original splendor can often be found next door to its vinyl-sided duplicate. One can easily imagine the Olde Bostonian of yesterday running off with the latter’s gutted detail. But the Olde Bostonian of today would much more likely be selling it back.

Contact Ben Berke at ben.berke@gmail.com. Follow him on Twitter at @benjberke.