US mourns a decade after September 11 terror attacks.

9/11 10th Anniversary. Weekend of remembrance.

9/11 Memorial at Ground Zero: first pictures revealed at 10th anniversary.

Thousands of people, family members of the victims killed in New York on September 11 2001, gathered this morning at Ground Zero as United States began a sombre day of tributes to those who lost their lives during the terror attacks that shocked the world ten years ago.

Today’s ceremony has moments of silence to mourn those who perished as each of the planes crashed and the two towers went down, while President Barack Obama and his predecessor George W. Bush deliver readings of the names of the 2,753 people who died in the terror attacks.

Thousands of family members of the victims killed in New York on September 11 , gathered this morning at Ground Zero for 10th anniversary from the terror attacks

New York forms the focus of the memorial day, but respects will be paid throughout the country, with events at the Pentagon and in Pennsylvania also poignantly marking the passing of innocent Americans a decade ago.

First moment of silence will be held at 8:46 a.m., when the first plane crashed into the North Tower, and then the names of the victims will be read.

Further moments of silence will be held to mark the other attacks in New York, Washington D.C., and Pennsylvania at 9.03am, 9.36am, 9.59am, 10.03am and 10.28am.

President Barack Obama and his predecessor George W. Bush participating at the September 11 10th anniversary at Ground Zero

The annual “Tribute in Light” will then begin from the World Trade Centre site at sundown, visible for more than 60 miles. Two blue lights, made up of 7,000 watt bulbs, were switched on for the first time this year on Tuesday night.

Law enforcement agencies around the country have stepped up security at airports, nuclear plants, train stations and elsewhere in anticipation of possible anniversary attacks.

New York City residents and workers in the area of Ground Zero are required to carry identification to gain access with 20 downtown streets planned for closure.

September 11 2011 also marks the opening of the memorial and museum, set in the footprints of the original Twin Towers of World Trade Centre among a small forest of oak trees in an eight-acre plaza.

The Ground Zero pools have the September 11 victims' names etched around their perimeters

The memorial, which opens to the public tomorrow, features two 30 ft-deep pools, each containing fountains, along with a museum with exhibitions and artefacts to teach visitors about the events of September 11. The Ground Zero pools have the September 11 victims’ names etched around their perimeters.

Yesterday, more than 4,000 people, including relatives of those killed when Flight 93 crashed into a rural Pennsylvania field, attended the memorial service in Shanksville.

Former President George W. Bush paid tribute to the victims of Flight 93 on Saturday, describing their actions as some of the most courageous in U.S. history.

George W.Bush was joined by former president Bill Clinton to lead a silent tribute to the victims of September 11 at the Pentagon and in Pennsylvania the day before the official anniversary of the terror attacks.

A long white stone wall bearing the names of those who struggled with al-Qaeda terrorists on the fourth airliner to be hijacked on September 11, 2001, was unveiled on the rural Pennsylvania field where the Boeing 757 crashed.

Current vice president Joe Biden joined the former presidents, families of the victims and several hundred others – many in patriotic T-shirts or holding US flags under a slate grey sky.

During the ceremony, the names of the 40 victims were read out, one by one, accompanied by chimes.

2,753 Flags of Honour – each baring the names of 9/11 victims in patriotic stripes of red and blue – are standing at the tip of Manhattan as New York City marks the tenth anniversary of the terrorist attacks.

The New York City Memorial Field, part of a five-day installation, was erected to give New Yorkers a public place to gather in remembrance of those who were killed in the horrific acts of September 11, 2001.

2,753 empty chairs, representing the lives lost on 9/11, were set Friday in Manhattan in order to face south toward the World Trade on Bryant Park’s lawn for part of a project called “Ten Years Later, A Tribute 9/11”.

Actors and performers from the Broadway community gathered at Times Square in costume for “Broadway Unites: 9/11 Day of Service and Remembrance” ceremony.

Organizers at Manhattan Community Board said the event is open for those who feel excluded from today’s official 9/11 Memorial ceremony, which is only open to families of the victims. Events to mark the tenth anniversary will go on throughout today in Manhattan.

The Metropolitan Museum of Art will display the 9/11 Peace Story Quilt with an accompanying programme throughout the afternoon.

Graduate students from New York University will read poetry from the quilt and a free concert will be performed. Created in collaboration with New York City students aged between 8 and 19, the quilt was made to convey the importance of communication among cultures and religions to achieve peace.

The New-York Historical Society will showcase a selection of photos taken during the immediate aftermath of the attacks on the World Trade Center. The Remembering 9/11 photo exhibition will be on view until April 12.

A film titled “World Trade Center: All Times”, based on a 10-year project by Fred J. DeVito that began as a way to remember the events and how they shaped the lives of Americans, will play at the Big Screen Plaza in Manhattan’s Flatiron district.

The New York Mets will hold a tribute at Citi Field at 7:30 p.m., half an hour before their game against the Chicago Cubs begins. John Franco will throw the first pitch to Mike Piazza – both members of the 2001 team.

Ground Zero "Tribute in Light" uses 88 powerful beams and has been running every year to mark the anniversary of the attacks

An Evening of Light 10th Anniversary Gala will be also held at Capitale at 8:00 p.m.

FDNY 10th anniversary memorial service honouring members lost at World Trade Centre, a free ceremony at St Patrick’s Cathedral, will be held from from 2:00 p.m. to 4:00 p.m., honouring the 343 FDNY families that lost a loved one at the World Trade Center. The ceremony will be shown on large TV screens in midtown Manhattan.

At the end of the day, St Patrick’s Cathedral will hold a free concert given by the Young Peoples Chorus of New York, the New York Choral Society, and Cathedral Choir of St Patrick.