The World Trade Center Memorial is due to open on September 11, 2011 on the 10th anniversary of the 9/11 attacks in lower Manhattan.

Registration began on June 11 for tickets to visit the tree-lined memorial plaza.

Those wishing to visit can go online and reserve a pass for a specific date and time. You can then enter the screening area during the half-hour block of time that is indicated on your pass.  Once inside, there is no limit on how long you can stay.

While the 9/11 Memorial is free, the site asks for an optional donation that goes towards sustaining the National September 11 Memorial and Museum.

The memorial plaza will include two large pools on the sites of the former skyscrapers amidst an urban oasis of trees.  It will accommodate up to 1,500 people at a time and tickets for the first few weeks were going fast.

Here's a sneak peek at the 9/11 Memorial as workers complete the final touches: