“Mayor Lindsay gave us a letter, so that if we were stopped by the police, if the police tried to stop us from saving the ornament that was being smashed willy-nilly, we could show the letter,” she recalled. “It said, in mayorly terms: ‘Cease and desist. These people have permission.’”

A stroll through the museum is an immersion in an era that began around 1875, when the city was beginning to climb skyward. That era lasted until just before World War I. Many of the carefully carved keystones and classical column capitals lasted until the heyday of urban renewal a couple of generations later, when wrecking crews pried them off.

“They weren’t saving anything,” Mrs. Karp said. “When a building was under demolition, Ivan would go up to the foreman and say: ‘See that up there? Bring it down gently.’ Ivan would give him $10 and go back at the end of the day, and the foreman would tell him where it was.”

The adventures of Mr. Karp, who died in 2012, fueled the recent novel “The Gargoyle Hunters” by John Freeman Gill, a freelance writer who has contributed to The New York Times and The Atlantic. He took the title from the headline on a 1962 article in The New York Herald Tribune’s Sunday magazine that he said described “a subculture of folks who haunted demolition sites to salvage endangered architectural sculptures during that period of sweeping urban renewal.” Mr. Gill said his mother had done some gargoyle hunting. He said he had heard about Mr. Karp from her, and tracked him down in 2009.

The museum is open only three hours a week, from noon to 3 p.m. on Sundays, and only three months of the year, from Father’s Day through August. Charlotteville is so far from the madding crowd that no one from New York “actually makes a trip here,” Mr. Dahms said. He added that local residents come for the second floor, a separate museum about Charlotteville itself that Mrs. Karp assembled.

The Karps spent summers in Charlotteville, but at first Mr. Karp did not publicize where the museum was because “he didn’t want artists besieging him with slides” to look at, Mrs. Karp said. The town had shown promise before the Civil War, with a couple of colleges and five general stores, but the colleges burned and the general stores foundered. Later a photographer from Vogue redid the town’s one hotel “as a getaway place for the models,” Mr. Dahms said, but he married one — “and she decided she wanted a castle in France, and they moved on.”