Strasbourg is situated on the III River, where it flows into the Rhine on the border with Germany, across from the German town Kehl. The city is situated in the Upper Rhine Plain,, approximately 20 km (12 mi) east of the Vosges Mountains and 25 km (16 mi) west of the Black Forest.

The location and the resulting poor natural ventilation makes Strasbourg one of the most atmospherically polluted cities of France, although the progressive disappearance of heavy industry  on both banks of the Rhine, as well as effective measures of traffic regulation in and around the city are showing encouraging results.