Walhalla
East of Regensburg, this mammoth monument is a none-too-subtle expression of 19th-century pan-Germanic nationalism. In Norse mythology, Valhalla was where the god Odin received the souls of dead heroes, and when Ludwig I erected this neoclassical Parthenon-style temple in 1840, it was to honor German heroes from ages past (more recent additions include busts of Albert Einstein and Sophie Scholl). The expanses of costly marble are evidence of both the financial resources and the craftsmanship at Ludwig's command.
Walhalla may be kitschy, but the fantastic view it affords over the Danube and the countryside is worth the trip alone. You can either drive here (parking's €2.50 for two hours) or, every day between late April and early October, take a charming two-hour boat ride from the Steinerne Brücke in Regensburg. Opt for a round-trip on the Swarovski-decorated Crystal Queen and Crystal Princess ships (€19.50 return), and prepare for a climb up 358 marble steps from the river to the temple.