The granite and steel gatehouse on West 119th Street was built during the cholera outbreak of the 1920s, fulfilling a need for access to clean water in the island of Manhattan. The greenhouse program, developed in the context of plant preservation in a climate emergency, generates an alternative definition of value on land that has, over time, accrued monetary and historic worth. My adaptive re-use project at this site retains much of the existing building material, and strategically re-orients the structure to prioritize plants and their solar radiation needs. The right triangle offers two meaningful effects: first, it densifies the available footprint of the small site by looking upward, and second, the long hypotenuse maximizes southern sunlight into the otherwise dark interior. Arctic plants naturally remain on the interior, while the native New York plants grow along the south wall. In the summers, the highest point of the structure receives over 12 hours of sunlight per day, supporting arctic plants especially. The triangle building is an altered memory of the rectangle with a pitched roof, an old emblem of the city’s modernization of infrastructure and interest in engineering hygienic water.