In a building damaged by debris from the Sept. 11 airliners that brought down the World Trade Center and soon to become a 13-story mosque, some see the bridging of a cultural divide and an opportunity to serve a burgeoning, peaceful religious population. Others see a painful reminder of the religious extremism that killed their loved ones.

Two Muslim organizations have partnered to open the mosque and cultural center in lower Manhattan, saying the $100 million project will create a venue for mainstream Islam and a counterbalance to radicalism. It earned a key endorsement this week from influential community leaders.

But some 9/11 victims' families said they were angered that it would be built so close to where their relatives died. "I don't like it," said Evelyn Pettigano, who lost a sister in the attacks, during a phone interview on Thursday. "I'm not prejudiced. ... It's too close to the area where our family members were murdered."

But the growing number of congregants at the only other nearby mosque, open only one day a week, created a need for an additional space for Muslim prayer in the neighborhood, said Daisy Khan, the executive director of the American Society for Muslim Advancement and a board member of the Cordoba Initiative, the two organizations sponsoring the project.