In 1806, Alexander von Humboldt and his team visited Chimborazo, a 6263 m colossal volcano in Ecuador. The extensive plant observations the team collected here and in the surrounding Andes Mountains, along with measurements of the environment, served Humboldt to define the new field of plant geography, the science of “what grows where and why”. Humboldt synthesized the main drivers of the distribution of life on Earth, spread the notion of the importance of climate on geographical patterns in nature, and recognized the role of humans in destroying nature through environmental change. Yet Humboldt’s legacy did not only provide the beginning of this new scientific field. His plant observations and collections give us a unique glimpse of what the distribution of vegetation along elevation gradients was in his time. In this chapter, we travel to the place where the field was born in the literal and figurative sense. We explore the changes that the vegetation of Chimborazo has undergone, and we look into Humboldt’s influence on plant geography and see how, generations later, plant geography—and biogeography in general—have gained prominence as fields for understanding, predicting, and addressing the impact of human-driven global change on biodiversity.