BAGHDAD // A massive bomb exploded at the United Nations headquarters in the Iraqi capital 10 years ago today.
Dubbed "the 9/11 of the UN", it killed 22 people and prompted heightened security measures that ultimately limited interaction with ordinary Iraqis.
A suicide bomber detonated an explosives-filled truck next to the Canal Hotel, which housed the UN offices, on August 19, 2003.
Brazil's UN envoy, Sergio Vieira de Mello, was among those killed.
At the scene of the attack - one of the first such bombings in Iraq - little has changed in the 10 years that followed.
One corner of the hotel still looks like it was smashed by a giant hammer. The remains of floors jut out from the building, rooms strewn with rubble and covered in dust.
Rusted metal reinforcing rods hang from the structure like vines that have long since withered and died, and a blue United Nations helmet still sits near the site of blast.
Marwan Ali, at the time a political officer for the UN mission, survived the attack because he went across the hall from the section of the building that was destroyed just before the blast.
The explosion threw him to the ground, but he was uninjured.
"I was given a new life," said Mr Ali, who is now the director of political affairs for the UN in Iraq.
"After the explosion, I went back to where my friend was, and then I found him dead, together with another colleague," said Mr Ali, who worked to help those who survived the blast. "It is the 9/11 of the UN. It has changed the whole security position."
Before the Canal Hotel bombing, and another blast targeting the UN the following month, Mr Ali said he had been able to travel around Iraq in an unarmoured vehicle.
After the attacks, many UN staffers were moved out of the country.
Most are now back in Iraq, but the UN headquarters is located in Baghdad's Green Zone, a highly secure area housing sensitive Iraqi government buildings and foreign embassies, which is difficult for most Iraqis to access.
The area is surrounded by concrete walls and defended by soldiers armed with weapons ranging from assault rifles to US Abrams tanks, while the UN facilities inside are protected by more walls and guards.
Staff travelling outside the Green Zone are escorted by guards and ride in armoured vehicles.
The measures, especially the move to the Green Zone, have limited the UN's contact with Iraqi citizens.
UN staff were able to maintain contact with Iraqi politicians and other figures but "we more or less lost contact with the population", Mr Ali said.
"The issue of movement is crucial for us," he said, as the UN needs "to interact and to get the real impression and to show visibility".
It is important for the "United Nations to be seen as helping - we are helping, but we are not seen" by the public, he added.
While increased security measures pose challenges, the UN is still active in Iraq and has staff around the country. The mission works on issues ranging from Iraqi-Kuwaiti relations, elections and national reconciliation to Syrian refugees and Iraqis forced to flee their homes by violence.
Salim Lone, the UN mission spokesman in 2003, is another survivor of the bombing.
On the day of the blast, he should have been in a meeting in Vieira de Mello's office, but instead had to work on a statement in his office across the hall.
"That is what saved my life," said Mr Lone, who was wounded in the neck by the explosion. Except for one person, everyone died who was in that meeting.
"My office was completely ruined. There was smoke everywhere ... you heard screams everywhere."
Mr Lone did not renew his contract with the UN after the blast and returned home to his native Kenya, where he is writing a book.
The attack "made me a very closed person ... and for many years, my memory was terrible" though this has improved, he said.
The UN has been targeted in other countries but "the first really substantive attack" was the one at the Canal Hotel, said Mr Ali.
The effects of that blast are felt to this day by both survivors and the UN as a whole.