Almost 150 years after Charleston's worst fire cut a mile-long swath through downtown, new research is shedding light on just how much change it wrought.

Most historic photographs showing Charleston in ruins after the Civil War, including the famous shot along Meeting Street with the Circular Church's hollowed-out shell, actually depict damage from the fire.

And it wasn't even caused by the war -- unless one considers that it began with a group of slaves who were taking refuge in the city. They had started a campfire, for cooking or warmth, at a window and sash factory at East Bay and Hasell streets, where the Harris Teeter supermarket stands today.

Students with the Clemson-College of Charleston graduate program in Historic Preservation have researched the fate of more than a dozen properties involved, said instructor Katherine Saunders, who also is the Historic Charleston Foundation's associate preservation director.

"It's not a Civil War event, but it's related to the Civil War because the firemen who were supposed to put out the fire have gone to the Confederacy," she said.

The fire began about 10 p.m. Dec. 11, 1861. By the following morning, it had spread south and west -- almost all the way to the Ashley River, consuming more than 500 homes, stores, churches and other buildings.

"It was hot and dry and windy, a perfect storm for this fire," Saunders said. "It just raced through town."

One person died --a slave woman who re-entered a burning building to save a mattress, Saunders said.

Some parts of the city were never the same, such as 155 Meeting St. where Henry Winthrop owned a home that he was renting out, according to research by student Liz Shaw.

After the fire, the Meeting Street property would never be residential again. A stone-carving business, McAlister's Funeral Home and a series of cafes later occupied the site until the Golden Eagle Motor Inn was built there in 1966. It's now a Days Inn.

Student Dan Watts researched the property at 130 Broad St., where the fire claimed a home. The property remained empty for two decades before a new home was built there -- a home that survives to this day.

"It signalled how devastating the fire was," Watts said. "Charleston as a whole -- not just the fire but from the war -- was just downtrodden."

Historian and author Nic Butler said the state bank extended fire loans but many defaulted, causing the rebuilding process to drag on for decades.

After the city's 1838 fire in Ansonborough, the city of Charleston created a committee on wooden and brick buildings, and it continued into the 1930s. "In many ways, it was the precursor to the BAR (Board of Architectural Review)," Butler said, adding that those who wanted to build in wood needed the committee's nod.

The Circular Congregational Church, where Thursday's 150th anniversary symposium will be held, was lost to the fire and later rebuilt in a different style. The Catholic Cathedral on Broad Street also eventually was rebuilt.

Meanwhile, the city was permanently changed by the loss of landmarks such as South Carolina Institute Hall, St. Andrew's Hall, the relatively new Charleston Theater on Meeting Street, Cumberland Street Methodist Church, and the Quaker Meeting House, Butler said.

"I think the big legacy of the fire was it was the last one that consumed a pretty significant portion of the city," he said. "The people in the firefighting business really woke up to the need to address the situation with the most advanced equipment available."

"There's never been a big fire like that since 1861."