Remember the victims, the survivors, and the loss which humanity suffered due to the bomb blasts in 2001 and 1993.
To honor those 3000 people who were killed in those bombings, their names had been inscribed on the bronze parapets beside the memorial's 30 feet deep twin reflecting pond. This largest man-made waterfall (in North America) along with the memorial site is built on the actual location of the former World Trade Center. Also, seven stories below the ground in the Memorial's Museum (which is also the foundation of the former twin tower) one can know about the entire detailed history of the 9/11 event.
Don't forget to visit the famous "survivor tree" which survived the 9/11 event.