Robert Risko captures the larger than life Muhammad Ali in this unpublished illustration from 2015. Risko's inimitable, hard-edged, retro-airbrush illustrations have been celebrated by and featured in numerous esteemed publications and adorned book jackets, video covers and movie posters.

Muhammad Ali is photographed wrapping his hand during a training session for his fight with Alvin Lewis in Dublin in 1972. Ali won the match through a technical knockout, with the event and leadup captured in the 2012 documentary When Ali Came to Ireland.

Muhammad Ali is photographed leaning against the ring during a training session for his fight with Alvin Lewis in Dublin in 1972. Ali won the match through a technical knockout, with the event and leadup captured in the 2012 documentary When Ali Came to Ireland.

Muhammad Ali is photographed taking a break during a training session for his fight with Alvin Lewis in Dublin in 1972. Ali won the match through a technical knockout, with the event and leadup captured in the 2012 documentary When Ali Came to Ireland.

American professional boxer Muhammad Ali dons a protective Everlast sparring helmet while training at Deer Lake in 1975. Often referred to as "Fighter's Heaven" the training camp was where the legendary boxer would prepare for many of the big fights of his career.

Muhammad Ali is photographed shadowboxing for an audience at his training camp in Deer Lake in 1974. Often referred to as "Fighter's Heaven" the training camp was where the legendary boxer would prepare for many of the big fights of his career.

Muhammad Ali is photographed during a training session for his fight with Alvin Lewis in Dublin in 1972. Ali won the match through a technical knockout, with the event and leadup captured in the 2012 documentary When Ali Came to Ireland.

Muhammad Ali is photographed in the ring at his training camp in Deer Lake, Pennsylvania in 1977. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

Muhammad Ali is photographed shadowboxing at his training camp in Deer Lake, Pennsylvania in 1977. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

Muhammad is photographed taping his hands during a practice session at his training camp in Deer Lake, Pennsylvania in 1977. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

Muhammad is photographed in an Everlast sparring helmet during a practice session at his training camp in Deer Lake, Pennsylvania in 1977. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

Muhammad is photographed with his team at his training camp in Deer Lake, Pennsylvania in 1977. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

Former world heavyweight boxing champion Muhammad Ali is photographed training in Dublin for his fight with Alvin Lewis in 1972. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

Muhammad Ali is photographed resting on the ropes of the boxing ring at his training camp in Deer Lake, Pennsylvania in 1977. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

A sweat-drenched Muhammad Ali is photographed wrapping his hands at his training camp in Deer Lake, Pennsylvania in 1977. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

Muhammad Ali reacts after his first-round knockout against Sonny Liston during the World Heavyweight Title fight at St. Dominic’s Arena in Lewiston, Maine on May 25, 1965. The match was one of the most anticipated, watched, and controversial fights in the sport's history, and this split-second shot by Leifer is considered to be one of the most iconic photos of the 20th century.

They Must Fall: Muhammad Ali and the Men He Fought features powerful and often moving images and stories of Muhammad Ali and the men he challenged in the ring, by award-winning photographer Michael Brennan. Brennan spent decades locating Ali’s former opponents to discover what had become of them. Alongside the photos and stories of fighters such as George Foreman, Joe Frazier, Buster Mathis, Leon Spinks, and ‘Sweet Jimmy’ Robinson, this unique book is also a look through Brennan’s remarkable Ali archive, including time spent with great fighters at the Deer Lake training camp, press conferences and in the ring. This special edition, limited to only 50 copies, contains numerous never-before-seen photos plus poignant stories illuminating the images and contextualizing Ali’s powerful role in the world of sport.

Muhammad Ali celebrates after knocking out Cleveland Williams in the second round of the World Heavyweight Title fight at the Astrodome in Houston, Texas on November 14, 1966. Many experts and boxers, including Mike Tyson, regard Ali's performance in this fight to be the finest of his boxing career.

Muhammad Ali poses for a photo at his training camp cabin in Deer Lake, Pennsylvania on January 9, 1974. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

Muhammad Ali emerges from the darkness ready to fight during a photoshoot in Miami on April 2, 1965. Nicknamed "The Greatest", Ali is widely regarded as one of the most significant and celebrated sports figures of the 20th century and is frequently ranked as the greatest heavyweight boxer of all time.

Sonny Liston throws a right hook punch toward Muhammad Ali during the first-round of the World Heavyweight Title fight at St. Dominic’s Arena in Lewiston, Maine on May 25, 1965. The photograph captures one of the most anticipated, watched, and controversial fights in the sport's history, which Sports Illustrated dubbed the fourth greatest sports moment of the twentieth century.

Muhammad Ali is photographed conferring with trainer Angelo Dundee in his corner during the World Heavyweight Title fight versus George Chuvalo at Maple Leaf Gardens in Toronto on March 29, 1966. Ali went on to win both fights against Dundee through unanimous decisions on points. 

Muhammad Ali is photographed walking back to his corner during the World Heavyweight Title fight against Floyd Patterson at the Las Vegas Convention Center in Nevada on November 22, 1965. Ali would go on to win the match as well as a later 1972 fight against Patterson through technical knockouts.

A classic photograph of Muhammad Ali, this image was captured in the twelve days leading up to his match against the fearsome, hard-hitting heavyweight Earnie Shavers at Madison Square Garden in 1977.  Some years later, Brennan showed the picture to Ali who traced his right index finger over the sweat beads in the photograph and mumbled, "All them years, all them years of hard work."