The obvious question is: why did it take so long? Clearly, there were logistical issues - fires raged at the site for more than three months and it took 261 days to clear away the towering pile of debris. But more challenging still was satisfying the wide-ranging spectrum of opinion as to what should be done with this 6.4ha gaping hole in Lower Manhattan.
Mayor Michael Bloomberg originally wanted to build schools and apartments. Many locals wanted more cross-streets to improve traffic flow. The victims' families wanted a memorial.
Eventually, a master plan for the site was agreed. Half would be preserved as a memorial and a museum. The other half would contain four new skyscrapers and a major new transit hub.
The competition for the memorial's design attracted more than 5000 entries from 63 countries. The winning design, Reflecting Absence, was by unknown 34-year-old New York architect Michael Arad. His proposal turned the footprints of the Twin Towers into huge reflecting pools with waterfalls cascading down their sides and the names of the victims engraved around their edges. After years of political wrangling, soaring costs and fierce debates, construction finally started one month before the attack's fifth anniversary. Today, access to the memorial is via a free timed pass that must be booked online. When I visited, two days after it had opened, 500,000 passes had already been reserved. At the time of writing, it was possible to reserve a pass for the following day.
After passing through the requisite security checks, you enter Memorial Plaza, a spacious square with alternate smooth concrete slabs and rough cobblestones. You're immediately drawn to the pools, two gaping holes of 60sq m finished in steel grey granite. Water cascades 9m down each side into a main pool before disappearing into a central void whose bottom is out of sight. Softening the concrete and granite are strips of lawn and hundreds of swamp oak trees that will eventually grow to form a protective canopy.
In the middle of the plaza is a lone callery pear tree. It was found among the debris after the attacks, barely alive, with charred bark and snapped roots. Nursed back to health, it was named the Survivor Tree, an emblem of the resilience shown by the city and its inhabitants.
Another source of debate was how to arrange the 2983 names around the pools. Should the 343 firefighters be given special recognition? How can you honour family, work and friendship connections?
Eventually, a system was devised which arranged people into groups (by flight and tower, for example) but which also honoured meaningful connections, which could be requested by the victims' families. Twelve hundred requests for people to be located beside one another were made and, somewhat miraculously, all of them have been honoured.
To find a specific person, you can use a search tool on the memorial's website or consult one of the kiosks around the plaza.
When I visited, there were people from all walks of life, from camera-toting tourists to uniformed army personnel. Some made paper etchings; others placed flowers. Many just stood staring into the pools.
Arad said he wanted to create a "quiet, reverent place of contemplation that allows people to gather and to find communion with each other", and in that he has succeeded. The memorial feels appropriate. Respectful and moving on the one hand; engaging and resilient on the other. On September 11 next year, another layer of interpretation will be added when the 9/11 Museum opens.
What was as interesting as visiting the memorial was being in New York during the lead-up to the anniversary. Ten years on, it's clear the city is still struggling to make sense of the tragedy.
And though it's easy to focus on the negatives - the wars in Iraq and Afghanistan; increased airport security; the huge financial cost - there have also been numerous positives, from the formation of dozens of charitable foundations, to cultural events such as the Tribeca Film Festival, to the simple act of neighbours talking to one another.
For the 50 million tourists predicted to descend on the city this year, little has changed. New York is still the same bewildering, frustrating, intoxicating city it's always been, and forever may it stay that way.
TRAVELLERS' TIPS
Getting there: United Airlines flies from Auckland to New York via Los Angeles and San Francisco.
Where to stay: Andaz Wall Street is well-placed in the heart of Lower Manhattan. 75 Wall Street, New York.
When to visit: Free timed passes can be reserved at the 9/11 Memorial website.
Further information: See nycgo.com.
Rob McFarland was a guest of United Airlines.
