Germany became a unified state 150 years ago this week – and no other country has produced such original, provocative and powerful art since, from Richter to Klee, from Dix to Höch

Situated on the edge of the Alps, Neuschwanstein Castle may not look like the birthplace of modern art. Best seen from a perilously crowded footbridge across a vertiginous gorge, it floats in misty rains, a cloudy dream of white spires and battlements. Yet this 19th-century colossus is an architectural homage to one man: a composer who inspired the avant garde to make the leap to modernism.

Richard Wagner’s music so enflamed King Ludwig II of Bavaria, he built this magnificent medieval vision in honour of the composer. But, in artists across Europe, Wagner’s musical might released much more futuristic impulses. The abstract leitmotifs and unearthly symbolism of his operas fascinated artists from Aubrey Beardsley to Paul Cézanne. The impressionists, too, were entranced: Renoir travelled to Palermo, Sicily, to portray Wagner when he was composing Parsifal.