This Sunday marks the tenth anniversary of the September 11 attacks, and it also marks the opening of the National 9/11 Memorial, which transforms the empty void of Ground Zero into a peaceful place of remembrance. Architect Michael Arad’s design is no doubt beautiful and inspiring, but what else could the memorial have been? Arad’s design won the international competition, which received more than 5,200 proposals, each of which created a unique, reverent memorial. As we reflect on September 11 and prepare for our new landmark, take a look back at the other seven finalists to see what the memorial could have been.