A look back at 9/11 tributes through the years

In remembrance of the 21st anniversary of the Sept. 11 terrorist attacks, here’s a selection of photos from more than two decades of tributes, memorials and observances.

Also, keep scrolling for a look at 20 images that documented the enormity of 9/11.

Related: These 20 archive photos from the Associated Press document the enormity, chaos and emotion of 9/11 on every scale.