Joy Levitt, executive director of the Jewish Community Center on the Upper West Side of Manhattan, remembers her first conversation with Daisy Khan around 2005, years before Ms. Khan's idea for a Muslim community center in Lower Manhattan morphed into a controversy about Sept. 11, Islam and freedom of religion.
"Strollers," said Ms. Levitt, whom Ms. Khan had approached for advice on how to build an institution like the Jewish center — with a swimming pool, art classes and joint projects with other religious groups. Ms. Levitt, a rabbi, urged Ms. Khan to focus on practical matters like a decent wedding hall and stroller parking.
"You can use all these big words like diversity and pluralism," Ms. Levitt recalled telling Ms. Khan, noting that with the population of toddlers booming in Manhattan, "I'm down in the lobby dealing with the 500 strollers."
Clearly, the idea that Ms. Khan and her partners would one day be accused of building a victory monument to terrorism did not come up — an oversight with consequences. The organizers built support among some Jewish and Christian groups, and even among some families of 9/11 victims, but did little to engage with likely opponents. More strikingly, they did not seek the advice of established Muslim organizations experienced in volatile post-9/11 passions and politics.
The organizers — chiefly Ms. Khan; her husband, the imam of a mosque in the financial district; and a young real-estate investor born in New York — did not hire a public-relations firm until after the hostility exploded in May. They went ahead with their first public presentation of the project — a voluntary appearance at a community board meeting in Lower Manhattan — just after an American Muslim, Faisal Shahzad, was arrested for planting a car bomb in Times Square.
"It never occurred to us," Ms. Khan said. "We have been bridge builders for years."
How Ms. Khan's early brainstorming led to today's combustible debate, one often characterized by powerful emotions and mistaken information, is a combination of arguable naïveté, public-relations missteps and a national political climate in which perhaps no preparation could have headed off controversy.
As a result, supporters of the $100 million center, named Park51, which received its final approval from the city last week, are now beginning their fund-raising and detailed planning amid a broader battle. The future of the center — organizers say it will have a mosque, but its 15 floors will be mainly for other functions — has become grist for talk radio, cable television and election fights across the country.
Sharif el-Gamal, the developer on the project, said ironically in an interview Friday, "This might become the most famous community center in the world."
For American Muslims, the stakes have become painfully high.
"It has repercussions for the entire community," said Robina Niaz, who runs Turning Point, a group that fights domestic violence among Muslims. "What it has done is suddenly made it legitimate for everybody else out there to lash out at Muslims. It has brought us together. But it also shows how much work we have to do."
In 1999, Imam Feisal Abdul Rauf, Ms. Khan's husband, tried to buy the former McBurney Y.M.C.A. on 23rd Street in Manhattan, telling the seller's broker, David Lebenstein, that he planned a kind of Muslim Y.
Knowing that the 1993 World Trade Center bombing still left raw nerves in New York, the imam assured Mr. Lebenstein, "We're not the ones doing bombs; we're moderates and Americans."
The sale would have gone through but for financing difficulties, said Mr. Lebenstein, the son of a Holocaust survivor. Imam Feisal is in Malaysia and could not be reached for comment for this article.
Imam Feisal, 62, moved to the United States as a teenager with his father, an Egyptian imam, and graduated from Columbia University. Until 2009, he was the Friday prayer leader at Masjid al Farah, a mosque in the Sufi tradition, which emphasizes mysticism and tolerance. The mosque was established two decades ago and is 12 blocks from the World Trade Center.
His sermons were infused with a "sweet spirituality," not focused on "rules and regulations" or politics, said Adem Carroll, director of the Muslim Consultative Network, an advocacy group based in New York. Those sermons attracted his two allies in the current project, slated to be built at 45-51 Park Place.
Daisy Khan, who immigrated, also as a teenager, to Jericho, on Long Island, from Kashmir, married Imam Feisal in 1997. They founded a Sufi organization advocating melding Islamic observance with women's rights and modernity. After 9/11 they raised their profile, renaming the group the American Society for Muslim Advancement and focusing on connecting Muslims and wider American society. They spoke out against religious violence; the imam advised the F.B.I.; his wife joined the board of the 9/11 memorial and museum.
A few years later, Sharif el-Gamal, a developer whose Egyptian father was a Chemical Bank executive, asked the imam to perform his wedding.
Mr. Gamal, who headed SoHo Properties, agreed around 2006 to join the effort. In 2009, he bought two adjacent buildings on Park Place, where the imam began holding services. Only then did the organizers start reaching out more widely about their idea.
On top of the fear and confusion in New York about Islam after 9/11, a movement had begun to spring up against Muslims seeking a larger role in American public life. In 2007, Debbie Almontaser, a Muslim educator, had been forced to resign as the principal of an Arabic-language public school in Brooklyn after such groups helped paint her as supporting terrorism.
But the center's organizers said they had little indication they were flying into a storm.
Ms. Khan had continued meeting with Ms. Levitt; she remembers worrying less about strollers than "the street cart problem" — where would Senegalese street vendors, a subset of Muslims working downtown, stow their wares while at the center?
Ms. Levitt remembers advising the organizers to line up potential members and financiers — for instance, Muslims throughout the region — before proposing a building. But Mr. Gamal said he wanted to first find property and make sure downtown residents and officials wanted the center.
If he promised something to Muslims and did not deliver, he explained, "I would lose face within my community."
Ms. Khan said they were confident Muslims would back the center and thought it more important to talk to politicians and leaders of other religious groups.
Leaders of Muslim advocacy groups in New York note the imam and his wife had not often worked with grass-roots Muslim groups, and wonder if they wanted to avoid appearing "too Muslim." The organizers say they did not.
Organizers talked with Mayor Michael R. Bloomberg about the plan in September 2009, at a Gracie Mansion Ramadan fast-breaking for Muslim leaders. A New York Times article last December about the project drew little negative comment.
In February, the staff of Scott M. Stringer, the Manhattan borough president, who liked the idea, suggested the organizers present it to Community Board 1, the largely advisory body that represents the neighborhood. Planners agreed to share information before the board and respond to expected questions about congestion and how the neighborhood could benefit.
Mr. Stringer said nobody warned them of "an Islamic issue," adding with a weary chuckle, "We really give good advice."
Preparing for a May 5 community board meeting, Ms. Khan got support from her usual allies, like the United Jewish Federation of New York; Trinity Church; and the September 11 Families for a Peaceful Tomorrow.
Some people raised concerns about the feelings of 9/11 victims, but the meeting was dominated by logistical concerns and support from those who welcomed new facilities downtown. The board gave a unanimous yes.
The next day, the uproar began. Some newspapers referred to the project as the "W.T.C. mosque." Mr. Shahzad had been arrested late on May 3 in the attempted Times Square bombing. The community board office began receiving "hundreds and hundreds" of angry calls, and e-mails from around the world, said its chairwoman, Julie Menin, some threatening enough that she requested riot police for the next meeting.
The organizers were shocked. Many supporters say that their failure to imagine the backlash left them ill prepared to defuse it.
On May 18, the organizers held a conference call with supporters, and soon hired a crisis public-relations firm.
Ms. Menin of the community board urged Ms. Khan and the mayor's office to hold a public forum to clear the air before the next community board meeting on May 25; they could, for instance, make clear that their congregation had worshiped in the neighborhood for years.
"It would have defused some of the problems, absolutely," Ms. Menin said. But the public forum was not held.
Nevertheless, the project's original backers held firm. When the city's Landmarks Preservation Commission on Aug. 3 removed the only legal hurdle, Mr. Bloomberg gave a passionate speech assailing the project's critics as trampling religious freedom. American Muslims — including some groups not initially consulted — rallied to the project's defense.
Mr. Gamal said that since May, he had started meeting in private with opponents to explain himself. But he bridled at constantly defending himself publicly. He said he didn't want to tell angry opponents how he had injured his eye handing out water to emergency workers on 9/11.
He didn't feel that he should have to, he said. He refused recently to appear on CNN to debate Rick A. Lazio, the Republican candidate for governor who has come out against the project.
"This is not a debate," Mr. Gamal said. "I'm an American. I'm a New Yorker. I'm exercising my freedoms in this country." There is little he would do differently, he said. "There's no textbook that you can follow."
Nor, it seems, a blueprint about what to do next.
On Tuesday night, organizers met with a wider range of 9/11 victim families. Ms. Menin is still calling for a town hall meeting.
"You have to deal with the uncomfortableness and controversy head-on," Ms. Menin said.