“A white elephant”in other languages

Same idea, different pictures

English takes its white elephant from a popular story about the kings of Siam: a sacred white elephant could not be put to work, so giving one to a rival courtier ruined him with its upkeep.

French keeps a dancer, entretenir une danseuse, as rich men once supported dancers of the Paris Opéra: an expensive indulgence. Italian builds a cathedral in the desert, cattedrale nel deserto, usually said of a big public project that never pays off.