In the run-up to this year’s Boston Marathon, commemorations of last year’s bombings and tributes to the survivors have been plentiful — and a new exhibit at the Boston Public Library may be the most dramatic memorial yet. But plans for a permanent memorial remain unclear.

Battered old running shoes, handwritten notes of support and sympathy from around the globe, heartrending photos of Martin Richard, Lu Lingzi, Krystle Campbell, and Sean Collier — these mementos were left by well-wishers after the Boston Marathon bombings, and spent the past few months in the Boston City Archives, shielded from the city’s brutal winter. But now they’re back in the public eye thanks to a new exhibit at the library entitled Dear Boston — and Mayor Marty Walsh says it serves an important purpose.

“Last year we were tested, and we this year we still feel grief,” Walsh said. “But what we see here is a tribute to how as a community we come through these tragedies. We turn to each other and offer whatever we have to give — a helping hand, a word of comfort, a token of hope.”