"I am struggling today," Nutter said. "I cannot even comprehend the pain and heartbreak that these six families are experiencing."
The victims did not die in vain, the mayor said, quoting Abraham Lincoln. The tragedy has prompted a review of city demolition practices, as well as an independent review of procedures and oversight.
The narrow strip of land where the store stood will become a memorial park. The Salvation Army donated the property to the city, with the official transfer taking effect last week.
The mayor vowed to do whatever he could to stop development on the adjacent lot, owned by developer Richard Basciano.
His company, STB Investment Corp., hired demolition contractors to remove a four-story brick building to make way for a new development. But because of sloppy work and lax oversight, a falling wall crushed the thrift store next door.
The victims were Anne Bryan, Mary Rosaline Conteh, Borbor Davis, Kimberly Finnegan, Juanita Harmon, and Mary Simpson. In addition, 14 people were injured, including Mariya Plekan, who was trapped for 13 hours in the rubble and lost both legs.
The most searing remarks Thursday morning came from the stepdaughter of Davis, Maryann McClain Mason.
"It's been one year," Mason said, looking toward the empty lot owned by Basciano, "and we've not heard from whomever owns the building that took away my dad."
A committee of citizens plans to raise funds to underwrite the cost of creating the memorial park. So far, the group has commitments of $165,000.
The Pennsylvania Horticultural Society has created a preliminary design for a park. The Pennsylvania Academy of the Fine Arts, meanwhile, is conducting a contest among students and alumni for a sculpture that will become a focal point of the park.
Maj. Robert Dixon, the Salvation Army's director of operations for greater Philadelphia, told the audience that the organization did not hesitate to turn over the property for a memorial park.
"We, too, have felt your loss," Dixon said. Two of the victims were employees of the Salvation Army.
Many neighbors who vividly recall the chaos of that morning last year attended the ceremony.
Frances Williams lives across the street at the Sidney Hillman Apartments for elderly and physically disabled residents.
From her window she watched the search and rescue efforts of firefighters. She recalled the mournful ritual of a silent ambulance taking away each body pulled from the site.
Then, 13 hours after the collapse, rescuers carried out a woman and an ambulance siren wailed.
"Everyone screamed," Williams recalled, "because we knew the woman was still alive."
The survivor was Plekan.
Ines Featherstone, 80, of Southwest Philadelphia, arrived at the ceremony with a bouquet of orange roses cut from her garden. She placed them where the birch was planted, in honor of Davis.
Featherstone said she shopped at the store regularly and knew Davis as the friendly clerk.
"That Friday I promised him I would come back on Wednesday," Featherstone said.
She said she remembers him telling her, "We've been missing you."