For older, dense cities, few images convey the plight of urban decay more than derelict commercial avenues. Block after block of once-prosperous main streets has been reduced to abandonment and marginal trades. Yet these places still often function as gateways, greeting visitors to urban America and creating indelible impressions of an area’s health and viability. No one formula exists for injecting life into these fallen urban commercial corridors. But using Philly streets as case studies, Ryan Briggs looks at four distinct strategies for redevelopment and revitalization, laying out challenges, reinvention process and the innovative fixes that may apply to streets in your own city.