The murder of President John F. Kennedy in Dallas, Texas, on Nov. 22, 1963, forever changed America. I was 16 years old when it happened, and still haven't fully come to terms with it. The indelible sense of loss and still-unanswered questions — How it could have been allowed to happen? Who was behind it? — drew me to Dallas nearly half a century later.

The trees in Dealey Plaza, where the killing took place, have grown taller, but the landmarks that appeared in the news broadcasts 50 years ago are immediately recognizable: the former Texas School Book Depository at 411 Elm St., which now houses a museum; the small sloping hill called the grassy knoll, with a stockade fence along its top; the triple underpass; and the concrete abutment midway down the slope, from which businessman Abraham Zapruder recorded "the saddest and most expensive 26 seconds of amateur film ever made."

Contemporary additions can be seen as well. In the center lane of Elm Street, two white letter X's have been painted, about 30 meters apart, to mark the approximate spots where JFK was struck by a sniper's bullets.