Once the seductive symbol of sophistication and unlimited possibility, the city has become synonymous in our imagination with sprawl, stress, pollution—even the propagation of disease. How do we reawaken the attraction humanity has so long felt toward these centers of trade, knowledge, and cultural exchange? And what must we do to make the city hospitable to both its inhabitants and the natural environment? The work of a business leader and world traveler rather than an urbanist, The Urban Challenge is a passionate argument for a redefined city model that favors sustainability and inclusion: a place where man and nature are no longer in conflict, and where the hallmarks of urban life, from mobility to housing, provide us with comfort, well-being, and innovative ways of living better together. Pierre-André de Chalendar is chairman and CEO of the Saint-Gobain Group, which he has transformed into a leader in urban housing renovation and sustainable construction. He is also the author of a previous book on climate and decarbonization, Our Fight for the Climate: A Carbon-Free and Growing World Is Possible (Le Passeur, 2015). “Cities are our most vibrant cultural and economic centers, but today they face an array of complex issues. The Urban Challenge helps us imagine how they can change and grow—and become greener, healthier, and more prosperous places for all.” Michael Bloomberg, founder of Bloomberg LP and Bloomberg Philanthropies, and former Mayor of New York City.