The Altmühl Valley (Altmühltal) is a natural park in central Bavaria, threading along the Altmühl River between Gunzenhausen and Kelheim. It is one of Germany's most popular cycling and hiking destinations, and it earns that reputation: limestone cliffs, medieval walled towns, Roman ruins, and a river wide enough to canoe make for a genuinely varied few days.
The main draw is the Altmühltal Radweg — a 160-kilometre cycling route along the river — and the parallel hiking trail. Canoeing the Altmühl between the towns is another classic. The valley passes prehistoric quarries at Solnhofen (source of the Archaeopteryx fossil), Roman Limes fortifications, and Pappenheim with its spectacular castle above the river. Eichstätt, the valley's main town, is a baroque bishop's seat with a good fossil museum.
The Altmühl-Donau canal runs through the valley, connecting the Rhine, Main and Danube — a feat of engineering that is also pleasant to walk or cycle alongside. The river itself connects a string of calm lakes well suited to camping and swimming.