Unlike many US cities, Philadelphia doesn't have as many urban renewal failures. Many attempts at urban renewal were fought off, including MANY highway proposals that would have possibly eliminated the advent of Philly's current renaissance.
Besides the construction of I-95 (Delaware Expressway) and I-676 (Vine Street Expressway), which sequestered Philly from the Delaware River and cut Center City off from North Philadelphia, respectively, I would say that the biggest urban renewal failure was the Callowhill Industrial District Plan. Before this project was implemented, the Callowhill District had a housing stock similar to that of Society Hill. Like Society Hill before it was revitalized, Callowhill was also a slum neighborhood. If this project would have never occurred, Callowhill could have undergone a similar renaissance to Society Hill.
http://hiddencityphila.org/2016/02/t...of-callowhill/