The absence of space startled me. The longer I stood there, the more I was struck by the weightiness of that lack of space. Next, I became emotional, which surprised me. I have been listening to the discussions and debates about the best ways to remember September 11 as the memorial site was created and the museum built, so I was eager to see the finished product. What I did not expect was how emotional I would become from a simple, powerful, and elegant lack of space. If you have not seen it, the memorial is a deceptively simple square shape outlining the former twin towers, with the water flowing down the sides and disappearing into the ground with the names of those killed carved all around the edge. 
As I reflected on my emotional reaction to the 9/11 Memorial, I wondered if this emotion I felt was anything similar to the emotions I witnessed at my previous visits to the Vietnam Memorial. I learned about Vietnam through discussions with my parents and other people who lived through it, as well as through classes, books, films, images and music. When I saw the Vietnam Memorial for the first time as a kid, it just looked like a long wall with lots of names on it. I thought it looked cool, how it grew, then diminished and disappeared. 
But then I saw the people at the Vietnam Memorial weeping, sitting in quiet reflection, running their hands over the names carved in that wall, and realized that my learning about the war in Vietnam was different than those who lived through it. More recently, I happened to watch an old episode of Mr. Roger’s Neighborhood with my daughter where Fred Rogers visited the architect Maya Lin, who designed the Vietnam Memorial Wall. I was struck by the simplicity of the design and the power of that design as she discussed her work in a way that children could understand. I am amazed by the ways that design can convey ideas so powerfully and am grateful to people like Maya Lin and Michael Arad and Peter Walker (who designed the 9/11 memorial) who can touch people so deeply with their use of space, line, color, texture, form, and design.
Memorials are particularly loaded sites when they mark a scene of death and destruction. When I toured the Oklahoma City bombing memorial with my students, I was struck by the thoughtful planning of the space, the careful chronicling of the events, and the reverence bestowed on the victims of that attack. I was a kid when the attack happened and remember it, but not as clearly as most adults. At that particular visit to the memorial, my daughter was just 1 year old, and the photos of all the children in the daycare center that were killed in that attack made me view the memorial and event in a different way. 
My students were born long after the Oklahoma City bombing. They did not have the same sense of loss, remembrance, or reverence that I did as someone who remembered this event. But I did not fault them for that. After all, I have no memories of the majority of history – including more recent events such as Vietnam or World War II. But it does seem that memorials have a particular meaning to those who remember those events and a slightly different meaning to those who are learning about the event for the first time.
I toured the 9/11 museum and realized that this was the first museum I ever visited on a topic that I remembered thoroughly. An odd feeling for a historian. I remembered the 9/11 news reports, the photos, the images, the sounds, and the reactions. It was particularly fascinating for me to see how those of us who lived through this event made choices on what to include and not include in the museum. I also realized that many of the people in the museum were too young to have lived through 9/11 and many others were not American and visiting from other countries. Still others had personal connections to the event or the victims. 
My grandpa passed away recently at the age of 98, and he was in his upper teens when World War II began. In the next few years, very few WWII veterans will be alive any longer. Like most events in history, it looks different when the generation that lived through it passes away.
How do we memorialize events in ways that give meaning to those who lived through it as well as those who know nothing about it?
It’s remarkable how these memorials that you mention give space to grief in a way which most of our more heroic war memorials did not, like Grand Army Plaza here in Brooklyn.
Thank you. I was also deeply moved by impressions created by Oklahoma City’s Memorial.
Thanks for the question: “How do we memorialize events in ways that give meaning to those who lived through it as well as those who know nothing about it?” And thanks for picturing and reminding me of these memorials. My mind often pictures and juxtaposes two South Dakota memorials, the well-known Mount Rushmore Memorial and the slowly developing Crazy Horse Memorial which most people “know nothing about.”. Being a visual person, I’m grateful that God has gifted us with lots of Memorials… to re-member the lives of people and events and to become aware of his presence in the history of all of us.
My feelings about the Vietnam memorial are more ambiguous than yours. I started seminary in 1972. Seventeen students were in the Junior class. We left in June for our summer supervised ministry (field education) assignments. In September, only 8 of the 17 in my class returned. What happened? The Vietnam War finally ended and those 9 who did not return to seminary were in divinity school only for the deferment. When I first walked through the memorial I was deeply disheartened also, but muttered (under my breath) “What a waste.” I honor their service, but not the waste of human blood. We slaughtered well over one million North Vietnamese, most civilians. The “best” war memorial I have even seen is the Korean War memorial in DC. It is haunting. Over sized soldiers are marching and the artist captured the “thousand yard stare.” It truly captures the horror and senselessness of war. The day when men beat their swords into plowshares cannot come soon enough.
I had the privilege of being a deployed chaplain at the National 911 memorial opening. During my time there I ministered to survivors, first responders, and families of those who died. It is, indeed, a sacred place where I comforted, and prayed with, a number of those who survived, and family members of those who did not. I encourage everyone to make the trip there.