The modern slum is as prevalent as its stereotypes. Today, a slum is often understood to be a place of extreme poverty in the developing world-a place disordered, lacking the basic amenities of life, traumatized by violence, and perpetuated by dysfunctional families and disaffected extremists. Yet the word "slum" was not coined in the twenty-first century's developing world or its recent past. The word emerged in early nineteenth-century London, and...