Chattanooga native Steve Winningham was at work on the 23rd floor of the 47-story World Trade Center Building 7 when the first plane struck its 110-story sibling across the street on Sept. 11, 2001.
It's a day he stills struggles with, 20 years later.
Winningham, 65, has a law practice in Chattanooga now. Back then, he was a special trial attorney in the IRS Office of Chief Counsel.
Like most New Yorkers, he was starting a typical Tuesday. Unlike most, his desk faced the World Trade Center's north tower.
"I was sitting at my desk when I hear this boom across the street and look up, and it's just sort of like somebody ripped a tin can open up there. There's papers flying everywhere. It was like a ticker-tape parade in hell with the flames," Winningham said.
He made a quick call to his mother in Chattanooga to warn her of what she might see in news coverage of something happening in New York, he said. He told her he was OK, but he was still unsure of what was going on.
The World Trade Center was a complex of seven buildings opened in 1973, with the two main towers hailed as the tallest buildings in the world at the time.
The north tower, 1 World Trade Center, was 1,368 feet tall. Its southern twin was 1,362 feet tall.
The two were surrounded by five other buildings that comprised more than 13 million square feet of the center's office space.
On Sept. 11, Winningham sat at his desk in Building 7, facing the north tower across Vesey Street.
Unlike the twin towers, Winningham's building wasn't struck by an aircraft nor doused with jet fuel but succumbed to fire after the north tower collapsed beside it and set it ablaze, according to Federal Emergency Management Agency assessments.
The sprinklers didn't function, a likely culprit in the seven hours of uncontrolled fires that finally claimed the building around 5:20 p.m. when it collapsed, the reports state.
From his perspective inside and below the locations where the two planes hit the twin towers, Winningham couldn't tell how severe the damage was.
"We're turning on the radio, trying to figure out what was going on, and I'm kind of walking up and down the offices, and I went to my supervisor's office that looks out on the plaza," Winningham recollected.
He wanted to think it wasn't as bad as it appeared. He'd been there in 1993 when a terrorist detonated a bomb in the underground parking garage of the north tower.
"You're basically thinking, 'Well, do we need to leave?'" he said.
"So I went to the middle office kind of looking at the plaza, and then you start seeing people jumping out," he said, quickly cutting off the image in his mind.
"I couldn't see anybody land but then I decided — well, we're just going to have to go."
Winningham headed back through his floor to his own office when someone said a second airplane hit the south tower, "then we just left," he said.
He made his way home, turned on the news and saw he'd missed numerous phone calls on his landline phone.
"It was 30 to 40 minutes later, you just hear a rumble, and I looked out," he said. "The second one fell first."
"It was a beautiful day, and it just blotted out the sky, because I guess the wind was blowing my way. It was just dark as night," he said. "Then the other one fell.
"We saw all these people all covered with dust, walking around. We tore up some sheets and went down and gave people masks and we had some water," he said.
No one was killed in the Building 7 collapse; Winningham knew people from the complex who did.
"I only wish I could remember more of the names of the people from our building, such as the head of security, who I spoke to every day, who perished bravely doing his job, and all the other ordinary people who met their fate out of the blue that day," Winningham said.
Sept. 11 "seems to be a sort of dividing line in my life between a kind of innocence and a sadder realization that the prospects of danger and loss are ever-present," he said.
For Winningham, images of the horror of that day aren't as painful as other images of the more innocent times, like those depicted in the opening sequence of the Mike Nichols movie, "Working Girl."
"That starts with an aerial close up of Lady Liberty's face and pans wider out over New York Harbor to one of the Staten Island ferries chugging towards Manhattan in the morning rush, then continues circling around to show the destination, lower Manhattan, with the Twin Towers dominating the skyline in the morning light," he said.
That, he said, is "where I start to get choked up."
"The sequence continues as Tess and Cyn get off the ferry and zoom through the revolving doors of 7 World Trade Center past the huge painting of brightly colored concentric circles that dominated that tall atrium lobby and into the elevators that I took every day — it gets me every time I see it," he said.
"With Carly Simon singing 'Let the River Run' in the background, it is for me the most touching memorial of what was lost," he said.
"They say that 'nostalgia' in the Greek literally means 'the pang of remembrance,' and that sequence brings back to me the simple, cheerful, daily routine of thousands of workers going about their business reporting to work in that grand setting that was so shockingly obliterated on that otherwise beautiful morning," he said.
"Lower Manhattan was horrible for months after that and never really was the same."
Contact Ben Benton at firstname.lastname@example.org or 423-757-6569. Follow him on Twitter @BenBenton.