Dealey Plaza is a depression. It's a shallow basin on the western edge of downtown, framed by concrete structures called pergolas and peristyles that were built in the late 1930s by the Works Progress Administration. Designed as a gateway to the city, the plaza is more of an ode to the automobile, because the broad lawn is sliced by three streets: Elm, Main and Commerce. They slope from east to west and converge beneath a rail line in what is known as the triple underpass.

That's where President and Mrs. Kennedy were headed, on Elm, when the ghastly thing happened.

Dealey Plaza
A plaque marking the history of the Texas School Book Depository is mounted directly below the sixth floor window where the shots were fired in the assassination of President John Kennedy on Nov. 22, 1963. The distance from the window to Kennedy’s limousine was just 88 yards. -- Washington Post photo by John McDonnell

On the north side of the plaza is the famous grassy knoll, where the second shooter supposedly lurked. There's a second grassy knoll on the south size of the plaza. And the grassy knolls aren't actually knolls (as in, a hillock, a mound), but rather are just slopes on the rim of the plaza.
The place hasn't changed much since Nov. 22, 1963. Some signage is different. Skyscrapers loom in the distance. The live oaks are bigger. Otherwise, it's remarkably preserved, including the building on the northeast corner of the plaza, which in 1963 was a warehouse known as the Texas School Book Depository. Up there, behind a pile of boxes in the southeast corner of the sixth floor, Lee Harvey Oswald pulled the trigger.

"It's smaller than I thought it would be," Kimberly Feare, 52, of Redwood City, Calif., said of Dealey Plaza on a recent Saturday afternoon. "But maybe it's dwarfed by the incident itself. It's such a huge thing."

There, off the cuff, from a tourist, is the central tension of the Kennedy assassination.

This was, as she noted, a huge thing, a moment routinely and almost numbingly cited as an end to our innocence, as the termination of postwar conformism and the beginning of the chaos and madness and rage of the 1960s. It killed the first television president, his death captured on film. The assassination has been, ever since, the subject of obsessive investigation. There is always more to learn, always another factoid to gnaw.

The official story, first promulgated by the Warren Commission, describes the assassination as the act of one man. The Oswald-acting-alone narrative is a small one, and kind of meaningless. The assassination, in this telling of events, was an unlucky alignment of the stars. Which suggests that history can pivot more or less randomly. There is a special terror in that — the notion that huge things can happen for no good reason.

Against that story comes a wide variety of alternative narratives. Many invoke that second gunman on the grassy knoll. Or perhaps multiple gunmen. Or as many as 10 shots in Dealey Plaza. Oliver Stone's "JFK" has three separate sniper teams.

Here's Patti Martin, 52, of Oklahoma City, standing in Dealey Plaza a few feet from where Kennedy was hit in the head: "There's too many gaps. There's no way there was one gunman."

The gaps, the unknowns, the inconsistencies . . . the shadows . . . the "coincidences" . . . the anomalies . . . the things that just don't seem right.

Patti Martin: "Why would he have waited until here?" Meaning this spot on Elm. "He had a perfect shot at that corner." (In fact, he'd already taken two shots, closer to the corner.)

Depending on your theory, the assassination was the work of the CIA, the KGB, the Mafia, Castro, the anti-Castro Cubans, the Dallas police, Lyndon Johnson's Texas cabal, the limousine driver, Texas Gov. John Connally or the Secret Service (in one version, a panicky Secret Service agent heard the shots, pulled his assault rifle and accidentally killed the president).

The conspiracy theorists have one advantage: They don't have to have all the answers, merely enough questions and doubts to shatter the mainstream consensus. The Lone Nut orthodoxy is essentially a closed narrative — it all but says, "Keep moving folks, nothing to see here" — while the conspiracy theories are self-sustainingly open-ended, a perpetual-motion mystery that will be with us forever.

And they do one more thing: They bequeath the assassination a deeper layer of meaning. This is an institutional murder. The bad guys are powerful people in the shadows of our civilization. This is not some small event — it's an epic struggle between enlightenment and evil.

In this view, the official story is a theft of history. Freedom and justice and perhaps our cultural sanity require us to rescue the truth from a quagmire of lies.

For many of us, what we see at Dealey Plaza says a lot about who we are. It reflects a worldview. It reveals how we process information. It even becomes part of our identity, like party affiliation or religious belief. And thus, as we study the facts, and scrutinize the images, and examine all the angles and trajectories, we are vulnerable to confirmation bias. Believing is seeing.

Dealey Plaza
Tourist stand in the middle of Dallas’ Elm Street to take pictures from the spot, marked by a X, where the fatal shot hit President John Kennedy in 1963. They are looking up at the Texas School Book Depository, left. The sixth floor window where Lee Harvey Oswald fired his rifle is on the right, the second row from the top. -- Washington Post photo by John McDonnell

It was on a concrete pedestal of the north pergola that clothing manufacturer Abraham Zapruder, accompanied by his receptionist, Marilyn Sitzman, stood with his 8mm Bell & Howell home movie camera and made what is surely the most scrutinized film clip in history.

And there are other films. The buffs know this. There's the Bronson film, the Muchmore film and the Nix film. They're not nearly as vivid and gut-wrenchingly graphic as the Zapruder film, but the researchers study them closely.

Orville Nix was filming the motorcade from a spot near Main Street, aiming his camera toward the grassy knoll. After the shots rang out and the president's limousine raced to Parkland Hospital, Nix went back to work. He didn't get his film developed right away because he hadn't used the entire reel. The younger, digital generation may not fully grasp this concept. There was unused film, and he wasn't going to waste it.

The following Saturday — eight days after the assassination — he took the camera to a high school football game and filmed the majorettes performing at the halftime show. Only after that did he drop it off to be developed, and later got a phone call saying you better come down here, you've got a movie of the assassination.

Bill and Gayle Newman saw the assassination up close. They were the closest bystanders, other than the occupants of the limousine and the motorcycle cops. They were just 22 years old, with two small children, Billy, 4, and Clayton, 2. They wound up at Dealey Plaza and took a spot along the curb of Elm Street .

They're in a lot of the photographs and films of the assassination. They're the young couple on the ground, shielding their kids. Bill is seen pounding the ground with his fist. He remembers saying, "Some son of a bitch just shot the president."

Within 15 minutes, a WFAA station manager put the Newmans on live television and asked them what they'd seen. They held their boys in their laps as they spoke. They were clearly in shock. They told of the president shot in the head.

They slept that night, and for many nights thereafter, with their boys in bed with them and with a loaded 20-gauge shotgun close at hand. Because they were witnesses to this terrible thing and had no idea what that meant, and whether someone would come after them.

A couple of Saturdays ago, the Newmans, all four of them, showed up at The Sixth Floor Museum at Dealey Plaza inside the Texas School Book Depository to talk about what they saw that day.

Bill: "The side of his head blew off and the white matter flew up and the red. And I turned to Gayle and said that's it, hit the ground."

Gayle: "You just see bits of flesh flying up and white matter. It was just terrifying to see."

Their eldest son, Billy, mostly remembers how strangers flagged them down and made them get into an unfamiliar car, and that worried him. And then they fed him at the TV station. Clayton doesn't remember it at all.

Where did the gunshots come from? Behind them, somewhere. The Newmans don't have a lot to say about the assassination itself that isn't visible to everyone in the Zapruder film. But here's the key fact: They were there. They were 15 feet away. They didn't see this on YouTube. They have the special status of having witnessed up close the crime of the century. They recognize that, someday, one of the Newman boys might be the last living witness to the assassination.

"I have recognized that we are part of history, even though we are just a small apart," Bill said.

They feel a duty to answer questions if a researcher asks, or if the museum needs help with its oral history collection, because they know how people devote their lives to digging into the assassination.

Bill Newman said he once asked a Dallas mayor, "Why does this keep going on and on and on?"

And the mayor said: "Bill, people will be calling you the rest of your life. People are still researching the Lincoln assassination."

Dealey Plaza
Dealey Plaza in Dallas, photographed in October, hasn’t changed much since Nov. 22, 1963. Otherwise, it’s remarkably preserved, including the building, left, which in 1963 was a warehouse known as the Texas School Book Depository. -- Washington Post photo by Jonathan Newton

Over near the grassy knoll, vendors have painted two X's in the center lane of Elm Street, representing JFK's approximate location when he was struck by bullets.

The first X, close to the book depository, is pure guesswork. No one to this day knows when, exactly, Oswald first fired, and whether it was the first or second shot that hit JFK and exited his throat. The second X, representing the final, fatal shot, is far more accurately located.

"If I were doing it, I'd move it back two or three inches. It's pretty close," said Gary Mack, the curator of The Sixth Floor Museum. He means that, based on his study of the images of the assassination, he'd move the X a couple of inches closer to the depository.

He used to be a hard-core conspiracy theorist, but he'll now tell you that Oswald did it and that virtually all conspiracy theories disintegrate on close inspection. He believes there's more to the story than what the Warren Commission reported. He thinks Oswald and the U.S. government were more entangled than the government has let on.

"There are enough of those holes in the story that make the conspiracy folks keep digging," Mack said. "What these conspiracy theorists don't know, that all cops and journalists know, is that there are always holes in stories."

Dealey Plaza simply in its physical existence represents a reality check on conspiracy theories. The distance from Oswald to Kennedy at the fatal moment was just 88 yards. Mack says that when hunters come to the plaza, they all say the same thing: You wouldn't even use the scope for that shot.

But the monstrousness of the deed will always create a reality-distortion field. This place is a portal to alternative histories. Looking closer doesn't seem to clarify much. Examine the breaking-news coverage from that day in Dallas and you will see, already, the fracturing of the narrative. Witnesses report seeing things we know didn't happen (the Kennedys holding a dog between them in the limousine). And they often fail to see dramatic things right in front of them, such as Jackie climbing precariously onto the back of the limousine after her husband was shot in the head.

It's as though people couldn't see, or mentally process, something that bizarre.

Dip a toe into Dealey Plaza and you find yourself immersed to the neck. Or deeper. This is not just a depression, it's a pit, an abyss, and you can easily slip all the way down, and the next thing you know you'll be looking for bullets beneath the turf. Your world will be framed by grassy knolls.

A word to the wise: Get the hell out of there. -- The Washington Post