Filled with tree-shaded lanes and flower beds, Bangalore has long been known as India’s Garden City. Two decades into the tech boom, the southern metropolis has a new nickname: the Silicon Valley of India, where glass-and-steel towers are going up as fast as old trees are coming down. Lester Rozario and Smruti Kamat, a Bangalore-based husband-and-wife architectural team, wanted to find a way to bring the green back into their city—both literally and figuratively. So when a young couple with a penchant for sustainable living asked them to design an urban home, Kamat and Rozario jumped at the chance. "The challenge was to find a way to seize our slice of sky," says Kamat, who led the project.