Walhalla by Danube riverboat — the marble Hall of Fame above Donaustauf
Glide upriver from Regensburg's old town to Walhalla, King Ludwig I's blinding-white Doric temple modeled on the Parthenon, then climb the monumental staircase to a hall of marble busts honoring the great figures of German history. Arriving by water — the way it was meant to be seen — is the bucket-list version: the temple appears on the bluff exactly as Ludwig staged it, and the colonnade frames a sweeping bend of the Danube. It is one of the most theatrical neoclassical monuments in Europe and the single must-do beyond the old town itself.