BROOKLYN, N.Y. -- Metal clanked, jump ropes swooshed and loud thuds echoed across Gleason's Gym in Brooklyn as athletes continued training as usual on Saturday.
But for owner Bruce Silverglade, the day was anything but ordinary.
Gleason's isn't just the world's oldest active boxing gym in the U.S.; it's a place where 134 world champions have trained -- and one of those champions was the late Muhammad Ali.
"It's a sad day for us, but we're still very proud to say that Muhammad Ali is part of Gleason's legacy," Silverglade told CBS News.
The gym, which opened its doors in the Bronx in 1937, remembered the boxer before he was the legend we all know today. In 1963, he was simply Cassius Clay.
The story began when trainer Angelo Dundee led a training camp for Ali at Gleason's before his fight against Sonny Liston in 1964. And that wasn't the last time Ali would set foot in the historic gym.
He came back several times after that, Silverglade said, but this time as the great Muhammad Ali.
"He's a great individual. He's actually left a mark on boxing," Silverglade said. "I consider him more than a boxing champion, more than a boxing hero: He's an American icon."
Several boxers in Gleason's gym agreed.
Bronx resident Jared Kersey, who grew up watching boxing with his dad, said Ali was his inspiration -- but it wasn't because of his fights.
"His personality was the reason why I wanted to be a boxer," the 25-year-old said. "His speeches, interviews, jokes -- little things like that made me want to box."
However, Ali's incredible speed and techniques can't be ignored.
"God gave him the ability to be a very, very good boxer, and he took that ability and raised the standards of the world," Silverglade said.
The champ was able to avoid punches, move around and make a very quick circle in the ring.
Today, when men, women and children come to Gleason's they ask trainers to teach them Ali's style of boxing.
Manhattan resident Jenny Cimaglia is one those people.
"[Muhammad Ali] was actually a childhood hero of mine," said 31-year-old Cimaglia on her first day at the gym. "I was attracted to the movement and the lyricism; I didn't really understand the politics, which as an adult I greatly appreciate and admire."
He was a role model for so many people, Silverglade said: "He's going to live on."