In 1932, the artist was commissioned to paint a 63-foot-long mural in the lobby of the new Rockefeller Center in New York. The mural was to capture the spirit of a new generation advancing into the bright future of a new era and would be titled Man at the Crossroads. Rivera was very controversial for his Communist views and created an image radically opposed to Rockefeller's notions of the American future. His mural attracted public controversy and disapproval during its creation. Before the mural's completion, the Rockefellers paid Rivera for his services but subsequently banned him from the building and ordered the artist's unfinished work to be destroyed. Rivera left and recreated the piece in the Palace of Fine Arts in Mexico City in 1934, but he never worked in the United States again. The finished mural he called Man, Controller of the Universe.
At the bottom left we see a small assembly of animals next to a human baby. An unidentified body is laid across a kind of dissection table while another, hidden person stands behind an x-ray screen; and the figure of Charles Darwin stands over them, his face placed next to the screen displaying a human skull. The x-ray machine and monitor are fitted with impressive (and daunting) gadgetry that makes allusion to the Industrial Revolution and modern scientific development of the period. The heavy piece of equipment is made of dark metal and threatening black knobs which rise at the top like two horns. And if the top of the machine is something of a "head" of its own (ironically, because its x-ray face displays the skeleton of a human), then it has been fitted with a hat in between the two "horns"—a large knob shaped like a Nazi helmet. To the right of this strange and unsettling scene are a group of interracial children, seated in rows like students in a classroom. Behind them is an image of the metropolitan public, poor and rioting, with riot police attacking them on horseback. The seated children all hold their heads up to gaze through a giant, telescopic lens that points directly to the center of the mural. On the left and above these scenes, rising up from the x-ray machine, is a towering Classical statue of Zeus. He is brandishing his characteristic thunderbolt, but his hands have fallen off and a crucifix necklace has been put around his neck (an inappropriate anachronism for the Ancient Greek pagan deity). From this out-of-place, Christianized Zeus pour forth World War I soldiers in gas masks, carrying bayonets and wielding flame-throwers while tanks and bomber planes swell the background of the scene. In a pocket on the left-hand side and centered near the middle is a nightclub scene featuring a crowd of women wearing low-cut dresses and John D. Rockefeller (Rockefeller Jr.'s father) drinking alcohol among them—despite his public support of the United States' prohibition laws. Moving over to the right side of the mural, we see a Communist rally underway as Friedrich Engels, Karl Marx, and Leon Trotsky stand around a red banner. In front of them, a line of working-class men sits on old artillery materials and the dismembered head of a broken statue. They also gaze intently into a giant lens as if expectant of an answer. Above this scene stands another Classical statue with an engraved swastika, whose head has fallen off (some of the working-class men at the bottom are sitting on it). Behind this statue stands the Soviet community, carrying red flags and organized in an ordered file. In a small pocket on the middle-right-hand side is the controversial image of Vladimir Lenin laying his hands on the masses—and to the right of that scene, a glimpse of an Aryan race of white-clothed athletes advancing forward. In the middle of the mural stands a titanic machine with parts resembling a microscope, an engine, an irrigation pipe, a clock, and a naval steering wheel. A pipe at the bottom plants itself into the earth, where a lush and bounteous soil produces plants of several different varieties, all of which bear ripe fruits and vegetables. Two microscope trays flank each other, pointing in the four directions of the mural's four edges. On one tray are illustrations of the cosmos, comets, stars, and planets; the other tray shows the tissue of the human cell. From one central pipe a mysterious and powerful hand holds out an orb which, according to the artist, displays the schematics of atomic chemistry and cellular biology. Sitting in control of it all, the great, overarching machine of the 20th century, is a working-class man with a stoic face.
Typical to his style, Rivera lays out a story in his mural, this one a metaphoric account of the Modern Age. The "crossroads" is a symbolic crossroads of industry, science, socialism, and capitalism. This heavily iconographic mural tells Rivera's story of mankind's entrance into the new, Modern Era, and his symbolism bears philosophical implications on the proposed pathway for man's continuance beyond the crossroads. The revolution of Communism occurring on the right side of the work clashes with the bleak picture on the left; and Rivera's stoic proletarian leads the way in the center. (In contrast, the mural which now stands as a replacement of Rivera's original artwork in the Rockefeller Center is entitled American Progress and contains the figures of Mahatma Gandhi, Ralph Waldo Emerson, and Abraham Lincoln.)