During the procession through Muhammad Ali's hometown of Louisville, Kentucky, fans run alongside the hearse to pay tribute. (0:35)

The processional carrying the body of Muhammad Ali arrived at Cave Hill Cemetery in Louisville, Kentucky, on Friday, where the boxing great was laid to rest in a private ceremony.

In keeping with Islamic tradition, "Ali" is the single word inscribed on the headstone for the boxing superstar, family spokesman Bob Gunnell said. Ali's coffin faces the Islamic holy city of Mecca.

Before reaching the cemetery, the motorcade stopped outside the fighter's childhood home, and hundreds joined in the moment to honor "The Greatest," many taking pictures while others broke out into a chant of "Ali! Ali!"

It was a key stop on a 19-mile route that wound its way through the legend's hometown as the city paid its final respects to the "Louisville Lip."

More than 100,000 people lined the streets for the processional, Mayor Greg Fischer said, citing estimates by Louisville police and city officials.

As the motorcade slowly made its way through Louisville after a delayed start, organizers announced that the public memorial service for Ali at the KFC Yum! Center had been pushed back to a 3 p.m. ET start.

The procession began around 10:35 a.m. ET, about 65 minutes after its scheduled start of 9:30 a.m., and arrived at the cemetery around 12:50 p.m. Seventeen cars made up the procession, including the hearse carrying Ali.

Fans cheered like spectators at one of his fights, pumped their fists, stood on cars, held up cellphones, signs and T-shirts, tossed flowers, and scattered rose petals as the champ went by. Truckers honked their horns in salute. Others looked on quietly and reverently.

Former heavyweight champion Evander Holyfield said the massive turnout is proof of Ali's role as a unifier. Holyfield said Ali is "probably up above, looking down and seeing all the different races come together."

The hearse carrying Muhammad Ali stops outside his childhood home in Louisville, Kentucky, as the crowd says farewell to the boxing legend. Jim Watson/AFP/Getty Images

The motorcade paused briefly outside the Muhammad Ali Center, where a makeshift memorial has grown since the boxer's death. Flowers from heads of nations, a framed copy of Sports Illustrated with Ali on the cover and artwork of Ali were among the possessions left outside the museum.

Former heavyweight champion Mike Tyson was a last-minute addition as pallbearer for Ali after taking a red-eye flight from Las Vegas to be in Louisville on Friday, according to Gunnell.

Gunnell said Tyson wasn't sure whether he would attend the service because of a prior commitment. He said Tyson was highly emotional when he learned of Ali's death and wasn't sure whether he could handle the emotions of Ali's memorial.

Other pallbearers include former heavyweight champion Lennox Lewis, actor Will Smith and members of Ali's family.

Ali's cherry-red casket, draped in an Islamic shroud, was loaded into a hearse and the pallbearers left the funeral home in a double file. Ali's nine children, his wife, two of his ex-wives and other family members joined the motorcade.

Speakers expected for the memorial service Friday include former President Bill Clinton, actor Billy Crystal, journalist Bryant Gumbel, Ali's daughter Maryum Ali and representatives from multiple faiths.

President Barack Obama was unable to make the trip because his daughter Malia is graduating from high school. Valerie Jarrett, a senior White House adviser, planned to read a letter Obama wrote to Ali's family at the service.

About 300 celebrities and dignitaries will be among the 15,500 in the crowd, Gunnell said.

The funeral procession for Muhammad Ali makes its way down Muhammad Ali Boulevard, which was named in the boxer's honor in 1978. AP Photo/Michael Conroy

Turkish President Recep Tayyip Erdogan left the United States prior to the memorial service. He and Jordan's King Abdullah were scheduled to speak at the funeral but lost their spots when other speakers were added later.

On Thursday, the Jenazah, a traditional Muslim funeral prayer service, was held at Freedom Hall in Louisville. About 6,000 people were scanned in for the service of the 15,000 tickets that were distributed, according to Kentucky State Fair Board spokeswoman Amanda L. Storment.

After the public prayer service, Ali's family observed a private funeral.

Ali, a three-time heavyweight champion, died June 3 in the Phoenix area at age 74. He designed the two-day memorial in exacting detail years before his death.

ESPN senior writer Arash Markazi and The Associated Press contributed to this report.