New Orleans marks the 10th anniversary of Hurricane Katrina with multiple events across the city.
At a memorial service, Mayor Mitch Landrieu recalled how residents had turned to each other for support.
Former President Bill Clinton later spoke at a concert in New Orleans.
Hurricane Katrina killed nearly 2,000 people and displaced one million in 2004. It was the most expensive natural disaster in US history and caused destruction along the Gulf coast.
In New Orleans, the failure of the levee system left about 80% of the city under water.
Mayor Mitch Landrieu led a sombre tribute to the 83 unidentified victims whose bodies lie in mausoleums at the city’s Hurricane Katrina Memorial.
“Though they are unnamed, they are not unclaimed because we claim them,” he said.
“We saved each other,” the mayor added.
“New Orleans will be unbowed and unbroken.”
Residents and community activists also gathered at the levee in the Lower Ninth Ward, where storm waters broke through and flooded the district.
After speeches, a parade took place through the neighbourhood, with some participants in colourful Mardi Gras dress.
Throughout the day, thousands took part in traditional musical parades through the city’s streets.
Former President Bill Clinton later spoke at a free concert at New Orleans’ Smoothie King Center.
He said the sheer magnitude of what had been accomplished in rebuilding the city should not be underestimated, but that more work needed to be done so that the lines that divided communities – such as race and wealth – could be erased.
A ceremony was also held at the Superdome arena that housed thousands of displaced people after the storm.
President Barack Obama visited the Lower Ninth Ward on August 27, praising “the extraordinary resilience of this city and its people”.
Although New Orleans has largely recovered from the disaster, some – particularly from the African-American community – feel left behind.
On August 28, former President George W. Bush visited the city. His administration was criticized at the time over its slow response and the issue remains a source of deep resentment in New Orleans.