Urban infrastructure is becoming a defining issue for design practice in the 21st century. Rising sea levels, growing populations, and other urban challenges are requiring massive re-investments in our cities. Communities around the world are making it clear however that they are ready to address these challenges in ways that go beyond mono-functional 20th century models for infrastructure. By approaching these necessary investments in conjunction with needed social and ecological improvements, investments in social infrastructure can work overtime to multiply benefits, and build constituencies and funding for their construction. Jeremy Alain Siegel, Associate at BIG NYC, discusses BIG’s approach to these emerging projects in New York City and internationally.