Events will be held all week across the city.
The iconic boxer's funeral will take place on Friday
The temporary honor can be seen near Madison Square Garden.
'My last photo of my beautiful father'
'I'm sorry to tell you this way, but Muhammad Ali has passed away'
'The Greatest' will be laid to rest on Friday in his birthplace Louisville, Kentucky. But the city is as divided by race and wealth as it was when Ali was still Cassius Clay, says Andrew Dewson
Morgan prompted criticism for claiming Ali was more racist than Donald Trump
Morgan prompted controversy for claiming the late boxing legend was more racist than Trump
'You’ve seen them at every boxing occasion and what people are frightened of is that they don’t want that to happen to you'
In 1974, Muhammad Ali told Michael Parkinson and a stunned chat show audience that the white man of America was "the blue-eyed, blond-headed Devil"
'The reason Ali struck a chord in the hearts of so many Americans was not just his great boxing skill – it was his incredible courage'
'Don’t tell me how much you love Muhammad Ali and yet you’re going to be prejudiced against Muslims in this country'
Barack Obama has led tributes saying the heavyweight boxing champion 'shook up the world'
No other moment in history did more to raise awareness of the disease, or to inspire the millions worldwide living with its cruel and often debilitating symptoms, than his lighting of the Olympic torch in Atlanta in 1996
He was asked what he wanted people to think of him when he's gone