But Ms. Temple appears to have been make-believe. “Charlotte Temple: A Tale of Truth” was a book written by Susanna Haswell Rowson and published in 1790. It is a Danielle Steele-style yarn about a young British girl who runs off to America with a soldier, only to be abandoned.

Despite its sad ending — its heroine dies after giving birth — “Charlotte Temple” was one of the country’s best-selling books for decades. Ms. Rowson fed speculation that her tale was nonfiction, writing in a preface, “I could wish my fair readers to consider it as not merely the effusion of Fancy, but as a reality.”

The book’s appeal ebbed. Still, Gwynedd Cannan, Trinity Church’s archivist, says she fields about three questions a year about the Temple grave marker.

On Wednesday, Ms. Cannan tried to get some answers. With some grounds workers and a chain-and-harness system — and with permission from the church’s lawyers — Ms. Cannan hoisted the slab to see if there was a burial chamber underneath. That’s normally the case at the graveyard, which is the resting place of Alexander Hamilton and the steamboat pioneer Robert Fulton.

No luck. Packed dirt greeted her instead. And for fear of disturbing any human remains that might be within it — the graveyard was a Dutch burying ground in the 1600s, before the larger burial vaults were in common use — they put the slab back in place.

“It wasn’t what I hoped to find,” Ms. Cannan said, “so the mystery continues.”

Some Rowson fans believe Charlotte Temple was actually Charlotte Stanley, a real-life resident of Manhattan in the 18th century.

They say that Ms. Stanley is actually buried at Trinity, and that in later years her last name was removed from the slab and replaced with Temple’s by admirers. But Ms. Cannan says the fact that both first and last names are on the slab makes her suspect that no one is buried beneath it, because a typical burial slab there bears just a last name.

She also noted that Ms. Stanley’s years and Ms. Temple’s years don’t match up neatly.

“There’s a lot of wishful thinking and romantic transference out there,” she said.

Complicating the research is that the church’s early records were destroyed in a 1776 fire.

But Ms. Cannan says there is another theory, that a stonemason who was building the current church in the 1840s out of the same brownstone used for the marker may have been responsible.

Perhaps, the theory goes, he was an admirer of the Charlotte Temple book and decided to fashion an impromptu memorial to her. If that ever happened, what it wrought is notable. For decades starting in the late 1800s, Temple aficionados left offerings on the slab, like hair, bouquets and burned love letters, according to newspaper accounts. Lovers would meet at the stone.

Today, though, the marker commands little attention.

In fact, Brent Robinson, 43, a cardiologist from Texarkana, Tex., visiting with his family on a recent afternoon, didn’t give it a passing glance — until a reporter pointed it out and told him who might be underground.

“No, it’s not about Charlotte’s Web,” he told his perplexed daughters, before moving on.