It's the X, painted on the road below, that is the most chilling site.
It's not a large X -- less than half the size of a traditional railroad crossing sign -- but it jumps out at you when viewed from that famous corner window six floors above the street.
It's the view Lee Harvey Oswald had that fateful day 40 years ago in November as he looked down the barrel of his rifle at the motorcade carrying then-president John F. Kennedy. Nothing has changed in that view over the 40 years, other than the addition of the ominous X. You can get the same viewpoint Oswald had on Nov. 22, 1963 by standing at the window next to the one from where his rifle protruded. The X will seem so close, so clear, so unobstructed.
Little has changed in Oswald's corner from that fateful day. They've removed the original window frame and placed it in a Plexiglas display in the sixth floor museum on the top floor of what used to be the Texas School Book Depository. Today the building is called the Dallas County Administration Building.
A Plexiglas wall surrounds Oswald's corner where the schoolbook packing boxes are stacked as arranged by Oswald to hide himself from fellow employees and on which to steady his rifle. The sniper's nest is re-created from police photographs taken at the time of the assassination.
The museum itself didn't open until 26 years after Kennedy's death.
Although you'll need to be well advanced from 40 to remember that day that stunned the world, most of the visitors joining me on the sixth floor appeared to be 40 or younger.
You won't have to line up to pay the $10 adult admission fee. The museum attracts about 450,000 visitors a year. Ironically, there's a notice near the ticket booth prohibiting guns in the museum. Remember, you're in Texas.
About 4,000 photos and artifacts are spread throughout the sixth floor, such as film of CBS anchorman Walter Cronkite choking up as he announces the death of Kennedy.
Portions of the famous Zapruder film run on a continuous loop, but it doesn't include the graphic fatal shot that hit Kennedy. Original newspaper front pages from around the world, plus radio reports and ticker tape newswire recall that historic day in Dallas.
A survey of major news organizations around the world has ranked the assassination of Kennedy as the sixth most significant news event of the 20th century.
One section of the museum deals with the various conspiracy theories and one display claims 80 per cent of Americans believe Oswald did not act alone in killing the president.
Outside the building you walk the conspiracy trail by climbing to the top of the grassy knoll overlooking Dealey Plaza and examining the wooden picket fence where some witnesses claim there was a second gunman shooting at the Kennedy motorcade as it rolled down Elm Street heading for the railway overpass.