It was Buffalo's darkest moments, and it may be the explanation for one of Buffalo's most unique hauntings in one its most unique places - Old Erie County Hall.

"It's a spectacular building an a spectacular sight designed by a couple of monumental architects from Rochester, whose buildings all do tend to get ghost stories," said local author and supernatural historian Mason Winfield.

Wedged between a mass of taller buildings in the heart of downtown Buffalo, Old County Hall is one of the region's architectural gems. But those of you headed there to attend a court hearing or to file paperwork with the clerk could bump into an uninvited guest, who passed away violently more than a century ago.

On September 6, 1901 President William McKinley was in Buffalo for the Pan American Exposition. After he entered the Temple of Music, assassin Leon Czolgosz shot him with a gun hidden in a bar towel. McKinley died from infection eight days later. In a noble procession, McKinley's flag-draped casket was brought to Old County Hall, where was was laid in state for all to see, including the man who murdered him.

"The assassin was tried and convicted here, and he was led by the body in state several times on his way to a court appearance, as if to shame him, looking at the very noble man, beloved president that he shot," Winfield said.

More than 150,000 people passed through the lobby of Old County Hall to pay their final respects to the fallen president. But, rumor has it, long after they moved his body out of this building, people continued to see him.

"There have been people reporting that occasionally they see a body on a table laid out in state, and as many of them are unaware, this is where President McKinley was laid out, the sightings are a little more convincing." Winfield said.

Today, a small plate on the floor surrounding by two flags in the lobby marks the sad moment in American history. But Winfield also believes the old building might be a portal for all sorts of paranormal activity because of what happened on its grounds before it was built in 1876.

"First of all, it's located on top of Franklin Square, which is an old cemetery," Winfield said. "Many victims of the burning of Buffalo in 1813, and veterans of the War of 1812 were buried there. There's a lot trauma, a lot of sudden deaths. And the graveyard was theoretically relocated, I think in 1875, to Forest Lawn. We know there are still bodies under there."

Perhaps Old County Hall's most famous deceased visitor isn't the only one still roaming its halls, long after their time on Earth.

REPORTER: In your professional opinion, is this county hall haunted?

WINFIELD: There is a lot of psychic folklore about that building. It's a very good candidate to be haunted.

For those of you who are interested, Winfield does a McKinley Ghost tour, among others, during the spring and summer.