Editor's note: Joseph Daniels is president and CEO of the National September 11 Memorial & Museum, a nonprofit organization that is responsible for the design and operation of the memorial at the World Trade Center site.
New York (CNN) -- There is new life at the World Trade Center site.
The first 16 oak trees of more than 400 that will line the National September 11 Memorial have been planted.
Together, they will surround the acre-size waterfalls whose structures have already been built in the footprints of the twin towers, around which the names of the nearly 3,000 people killed on 9/11 will be incised in bronze.
Standing among these first trees, one can now truly envision the finished memorial: the canopy of leaves overhead, glowing stretches of bronze panels, cascades of water falling away from sight, a reverential calm within one of New York's busiest neighborhoods.
Life on the memorial site also takes the form of hundreds of construction workers who know this project is much more than just another job; every day they build history on these eight acres at the sacred heart of the place known as ground zero.
Earlier this week, they installed two 50-ton steel columns that once ringed the north tower at what will be the entrance to the 9/11 memorial and museum. The columns, known as "tridents" because of their three-pronged tops, are no longer sheathed in the aluminum alloy that once made the twin towers shimmer. They are worn and they are scarred -- but they remain strong. And now they stand proudly upright once again among cranes erecting steel for new office towers and a transit hub.
The memorial will open in just 366 days.
It will open with the support of hundreds of thousands of contributors from all 50 states and 39 countries. It will open because of the passionate dedication of New York Mayor Michael R. Bloomberg, who serves as the chairman of the memorial and museum, and because of the unity of purpose displayed in recent years by all of the World Trade Center stakeholders, including the Port Authority of New York and New Jersey, which manages the construction.
And as the history of 9/11 continues to unfold and evolve in real time, we are designing a museum that we expect to open one year later.
I know, of course, that many wonder why the project hasn't yet been completed. Others wonder if it's too much too soon given our proximity to the attacks and the sacredness of the site. As Bloomberg has said, the process to rebuild has been an example of democracy at work, with tremendous amounts of input.
In the nine years since the attacks, thousands of voices have emerged with differing opinions about what to build, what to say and how to commemorate. This expression of opinion is representative of what the terrorists sought to destroy and could not: our freedom.
In downtown New York, around the country and the world, the implications of 9/11 continue to evolve -- whether through the current debate over the Islamic cultural center to the north of the World Trade Center site, the war in Afghanistan, the question of where and how to try terrorists, our airport security or simply how to teach 9/11 in a classroom of children who weren't even born when it happened.
Here at ground zero, now on the ninth anniversary of the attacks, we have a deep and clear obligation: to commemorate and to educate.
The threat of terrorism remains all too harsh a reality. The thousands of people killed nine years ago did what we do every day: They simply got up in the morning and went to work. By remembering them, we recognize ourselves in the story of 9/11 and our responsibility as survivors to overcome an atrocity that shook us to our core.
By remembering the more than 400 first responders who perished solemnly performing their sworn duty that day, we honor those who sacrifice for our enduring freedom, both here at home and overseas.
Over the past year, more than 1 million people have visited the 9/11 Memorial Preview Site, a small space near the World Trade Center, where plans for the memorial and museum are displayed. More than 75 percent of those visitors came from other countries. When the memorial opens, 5 million-plus visitors are expected each year -- people of different nationalities, ethnicities, faiths, people with differing opinions about the ongoing ways in which 9/11 continues to affect our world.
The memorial and museum will aspire to transcend those differences, bringing people together in the same spirit of unity that brought us together in the aftermath of the attacks nine years ago.
Each and every person working on the memorial has a responsibility toward our common goal. Our focus is on opening the memorial on the 10th anniversary of the 9/11 attacks. And while success is not built in, my confidence in it grows every day as I see firsthand the intense personal commitment brought to bear by so many.
Life on the 9/11 memorial site will continue to grow as we dedicate a memorial that will be a testament that our shared humanity is stronger than the hate that sought to tear us down that day.
The opinions expressed in this commentary are solely those of Joseph Daniels.