Arlon (anc. Orolaunum), a town of Belgium, capital of the province and 1(5 m. W. N. W. of the city of Luxemburg; pop. in 1867, 5,779. It is situated in the midst of forests on a ridge of the Ardennes, and is rapidly increasing in prosperity owing to its ironware, leather, and other manufactures. It was known to the Romans. At the end of the 18th century it was the scene of various engagements between the Austrian and French armies.