Events Tuesday are scheduled to begin at noon ET.
Three people were killed and 264 more were wounded as runners streamed towards the finish line of last year's marathon. This year's Boston Marathon — the 118th — will be run on Monday.
Memorial events include speeches by U.S. Vice-President Joe Biden, Massachusetts Gov. L. Deval Patrick and Boston Mayor Martin Walsh, along with remarks by invited clergy and victims' family members. There will also be a performance by the Boston Pops Esplanade Orchestra.
At 2:35 p.m., there will be a moment of silence at the marathon finish line.