LUGDUNUM, in Ancient Geography, the capital of the Segusiani in Gallia Celtica, situated at the conflux of the Arar and Rhodanus, on an eminence, as the Celtic term dune signifies; built by Manutius Plancus under Augustus, while commanding in that part of Gaul; and whither he led a colony. Now Lyons, capital of the Lyonnais.