Salman Abedi, a 22-year-old Briton of Libyan descent, blew himself up as fans were leaving Grande's concert in the northwest England city on May 22, 2017. Twenty-two concertgoers were killed, and police say more than 800 people were left "with physical and deep psychological injuries."
Manchester residents laid bouquets of flowers in the city's St Ann's Square, or left hand-written notes on Japanese maples that have been planted to form a "Trees of Hope" trail through the city. One note cited US Episcopal bishop Michael Curry's sermon at Saturday's royal wedding: "As a clever bishop said 'there is power in love.'"
Prince William and Prime Minister Theresa May are due to join survivors and emergency workers who responded to the attack for a remembrance service at Manchester Cathedral on Tuesday.
Greater Manchester Mayor Andy Burnham said it was a day to "come together."
Police say 100 investigators are still working on the case. The U.K. has issued an arrest warrant for Abedi's younger brother, Hashem Abedi, and is seeking his extradition from Libya — a far-from-straightforward process given that country's political chaos.