Singapore calls itself the Garden City, and it’s making good on that promise. Singapore’s meteoric rise launched a landscape of towering architecture in the compact city-state, and it’s now a case study in urban density. But as the metropolis continues to grow, urban planners are weaving nature throughout—and even into its heights. New developments must include plant life, in the form of green roofs, cascading vertical gardens, and verdant walls. That push to go green