Many 9/11 memorials (including Postcards, pictured above, on the Staten Island waterfront) have been erected in New York City since September 11, 2001. Here are the stories behind some of them.

Many 9/11 memorials (including Postcards, pictured above, on the Staten Island waterfront) have been erected in New York City since September 11, 2001. Here are the stories behind some of them.