Police heightened security in New York on Friday in response to a credible but unconfirmed threat of an al Qaeda plot to attack the city again on the anniversary of the downing of the World Trade Center towers by hijaked airplanes.

In Manhattan, police set up impromptu check points and searched vehicles, but New Yorkers took the security alerts in their stride as a normal part of their life.

Ahead of Sunday's commerative ceremonies at Ground Zero, there are signs that some New Yorkers are tired of it all.

Don't call it Ground Zero, don't use the term 9/11 widow and don't read the names of the dead, they say.

New York Mayor Michael Bloomberg wants people to stop calling the place where the Twin Towers once stood "Ground Zero," a term which implies violence on a nuclear scale.

Progress helps that argument. The new One World Trade Center skyscraper towers more than 80 stories above ground as it inches to its planned 1,776 foot height -- symbolic of the date of America's independence.

The memorial plaza is ready and the neighborhood has enjoyed a revival making it a trendy Manhattan place to live.

Some of those most devastated by the attacks no longer wish to be defined by it. Among them is Kristen Breitweiser, who became a widow, activist and author after her husband died when hijacked planes slammed into the World Trade Center.

"I don't identify myself as a widow anymore. I'm a single mom," Breitweiser, author of the 2006 book "Wake-Up Call: The Political Education of a 9/11 Widow," told Reuters.

Sunday's ceremony includes moments of silence marking when hijacked passenger planes hit the Twin Towers as well as when they collapsed. There will also be moments of silence marking when hijacked planes crashed into the Pentagon in Washington and a field in Shanksville, Pennsylvania.

President Barack Obama and former President George W. Bush will be among dignitaries joining victims' families to hear the reading of the names of those who died on September 11.