This article introduces the reader to the hitherto hardly noticed ethnographic work of the renowned Prussian intellectual und politician Wilhelm von Humboldt (1767-1835). Humboldt is best known for his theoretical contributions to various fields of study, including anthropology and liberalism. Complementing this predominant view, the article focuses on Humboldt's observations during his travels and stays abroad, thus showing that he also conducted empirical research. Humboldt's accounts of the French, Spaniards, and Basques are interpreted against the background of his liberal anthropology. In this way, the article shows that Humboldt gained new anthropological insights through ethnographic research, especially about liberal constitutions and the connections between body and mind, and between individual and community. This new look at Humboldt's anthropological work also throws a light on the relationship between anthropology and liberalism, which is often regarded as problematic in more recent publications. The article thus contributes not only to the history of anthropology, but also to current discussions on the crisis of liberalism.