Inside the Flag Lowering Ceremony in Louisville for Muhammad Ali

Ali "belongs to the world -- but he only has one hometown," mayor said.

Ali and his wife also co-founded the Muhammad Ali Center, "which promotes respect, hope and understanding" in Louisville and around the world, Fischer said.

Fischer said Ali "belongs to the world -- but he only has one hometown."

"We heard him in a way no one else could. As our brother, our uncle, and our inspiration," Fischer said. "I am so grateful that I had the chance to know him and see how he leveraged his fame to share his message of love, peace and compassion."

Fischer said flags on government buildings would remain at half-staff until Ali has been laid to rest.