Author, scholar, and antiquary.

Traveled widely in Europe. Assembled a renowned collection of historical and scientific curiosities, as well as books and art from dispersed monastic foundations. Also served as a diplomatic advisor and did pharmacological research. Edited the Kölnische Gemeinnützige Anzeigen … (later rechristened the Kölnisches Enzyklopädisches Journal) and published Epigrammatographie. Inschriften der niederdeutschen Provinzen (1801). Supported the French Revolution, even during the Terror; his fellow townsfolk ultimately turned against him, and he consequently left his collections not to the city but to the house of Hesse-Darmstadt.

Born near Aachen. Educated at Cologne, where he settled c. 1750.