“The tension between being in an oasis and being in the city is what makes this project so wonderful,” says Weiss. So she and Manfredi chose to introduce the building to the street with a generous entry plaza and a copper sawtooth roof that will age to the same color as BBG's 1917 McKim, Mead & White administration building down the block. The jagged roof covers a garden shop that sells plants and books and can operate even when the garden is closed. What at first appears to be a single building addressing the street turns out to be a pair of structures separated by a fritted-glass-covered breezeway. Walk through that breezeway and you can continue along a path to the Cherry Esplanade or duck inside to the second building, this one topped by a 10,000-square-foot green roof planted with 40,000 grasses, spring bulbs, and wildflowers. The building uses earth and plants, along with glass and steel, as essential materials.