On April 15, 2013, a bombing attack at the Boston Marathon killed three people and injured 264 more.

As the city mobilized for a manhunt, eventually tracking down brothers Tamerlan and Dzhokhar Tsarnaev, it also remembered those who had been standing near the crowded finish line on a fateful Patriots' Day morning. People began leaving mementos at a makeshift memorial in Copley Square — a T-shirt worn in the race here, a small American flag there.

When it was time, finally, for the items to be collected and carried away, members of the City Archives in Boston gathered the mementos. They've spent the last year processing and recording the objects, many of which will go on display back at Copley Square, this time inside the library, as part of an exhibit running April 7 through May 11.

Below, photographs of several of the mementos left behind. --Sarah Eberspacher

**All photos: REUTERS/Brian Snyder**