The deputy First Minister has led Northern Ireland tributes to civil rights hero John Lewis after his death at the age of 80.
The Georgia congressman was one of the 'Big Six' civil rights leaders, who included Martin Luther King Jr, and helped organise the 1963 March on Washington.
He was best known for leading some 600 protesters in the Bloody Sunday march across the Edmund Pettus Bridge in Selma.
He announced in December that he had been diagnosed with advanced pancreatic cancer.
Michelle O'Neill said she was "saddened" to learn of his death, adding: "John was a dear friend to those struggling for rights and equality in Ireland."
In 2013 Mr Lewis was part of a US Congressional delegation who joined John Hume and other Londonderry people in a march across the city's Peace Bridge.
SDLP MLA Justin McNulty said: "John Lewis's impact extended far beyond America's shores.
"His example inspired civil rights activists here too where, six years ago, he joined another remarkable civil rights champion John Hume crossing the Peace Bridge in Derry.
"His legacy on our island is a great one. He will be sorely missed."
Meanwhile, in Atlanta flags were lowered to half-mast indefinitely to honour Mr Lewis, who represented the city for more than 30 years in Congress.
The city's mayor Keisha Lance Bottoms said words cannot describe the loss
US President Donald Trump ordered flags at half-mast at the White House and all federal public buildings and grounds, including embassies abroad and all military posts and naval stations, throughout Saturday.
In a tweet, Mr Trump said: "Saddened to hear the news of civil rights hero John Lewis passing. Melania and I send our prayers to he and his family."
Former President Barack Obama said: "Not many of us get to live to see our own legacy play out in such a meaningful, remarkable way. John Lewis did."
Martin Luther King III, the eldest son of the civil rights activist, told CNN: "From a historical standpoint, there are few who are able to become giants... John Lewis really became a giant through his examples that he set for all of us."