ARLON, chief town, province of Luxembourg, southern Belgium, on a hill (1,24of t.) above the headwaters of the Semoise. Pop. (1930) 11,658.The Orolaunum of the Romans was a station on the Antoninian way connecting Reims and Treves, and the name is probably Celtic. Extensive views are obtainable f rom the church of St. Donat, which crowns the hill. Vauban turned it into a fortress in 1671, damaging the old Roman wall, the foun dations of which were practically intact. In the local museum are many Roman antiquities, including several large sculptural stones.