The tourist office is in a grand stone building, a block northwest of Pl Léopold, Arlon's main square. Even when closed, the office's noticeboard displays a useful list of accommodation contacts, albeit mostly in nearby rural villages.
Ask about guided visits to the Tour Romaine, a small but curious subterranean fragment of Roman stonework reached by a little tunnel.
To ride out into the pretty rural countryside there are a handful of mountain bikes to rent (per hour/day from €3/20). Electric bicycles cost a little more (€5/30).