For 73 years, it was a place that connected people, where soldiers once kissed their girls before going off to war.
It was a stop on the Sunset Limited between Los Angeles and New Orleans, until Amtrak suspended passenger service in 1996.
The station still has penny-tile bathrooms and two-story ceilings and a carved oak refreshment booth in the corner with an authentic icebox still intact.
The old chandeliers and ticket booth are still there. So are the train tracks and the circa-1923 luggage carts.
And so is a ghost named Fred.
"When you're up in the attic of the station, and you feel a tap on your shoulder, and you turn around and no one's there _ that's Fred," said Dudley Weldon, who has worked at Union Station since 2002.
It's a privately owned place of business now and visitors aren't encouraged, according to The Arizona Republic (http://bit.ly/Jv6w5W).
The fences and gates went up shortly after the passengers moved out, and the Sprint communications company that owns the building moved more of its equipment in _ wires and switch boxes and fiber-optic cables and the backbone of its network from Los Angeles to Fort Worth.
Union Station also houses connections for Verizon, American Express, Cox Communications and others _ a mass of voices and Google searches and video feeds that speed silently through cables in dark rooms on the second floor.
Weldon, 60, is in charge of building maintenance and security _ which means that he keeps tabs on the old place and all of its creaks and quirks.
Once, Weldon had a pair of installers up in the cable room during the evening hours, working on maintenance, side by side. Each, at different times, noticed a shadow of something _ or someone _ at the other end of the room.
"Out of the corner of the eye, it appeared that somebody was running across the floor," Weldon said. "And it occurred to them, `Who else is here?'"
That would have been Fred.
Fred is the heavy side gate that opens and closes, and opens and closes, solidly, steadily, back and forth, without enough wind to explain its doing so.
Fred is the presence that the air-conditioning guy felt in the attic, looking over his shoulder, complete with a chill.
For the record: Weldon says he is a skeptic but he has also felt the particular eek of Fred now and then, like "if somebody comes up on you from the rear, and you notice the change in the atmosphere right around you -- a brief rustling, an airflow."
Sometimes Weldon turns to greet the whoosh he feels approaching and finds emptiness instead.
James Kelly of Arizona Paranormal Investigations has been looking into the supernatural for 35 years and said he would love to get inside Union Station.
"Paranormal theories are just theories, no one can prove them," said Kelly. "And we try to look for natural explanations first before we go to paranormal explanations."
To confirm a ghost, Kelly and his teams use recorders to try to capture voices and sounds in empty rooms. They ask questions and can hear answers only when they play back the recordings.
Kelly said there are many reasons that a ghost would choose an old train station.
"Older places tend to be more paranormally active than new places. An older building can hold memory, or it can hold what we call residual energy _ basically things that happened in the past replaying themselves over and over," he said. "Another big theory is that emotions are somehow imprinted into the environment. Most haunted places are places where people gather: bars, brothels... Maybe they worked at the train station. Maybe they liked being there.
But Weldon won't allow the paranormal testing at Union Station.
"You can't come in here and set up your sensors looking for ghosts. It takes time out of my day to satisfy someone's curiosity," he said.
Information from: The Arizona Republic, http://www.azcentral.com