a grand, costly thing or project that is useless and expensive to maintain
O estádio virou um elefante branco: custou bilhões e hoje vive vazio.
The stadium became a white elephant: it cost billions and now sits empty.
The traditional account points to the old Kingdom of Siam (today Thailand), where naturally white (albino) elephants were rare and sacred. To ruin a courtier he disliked, a king would "honour" him with a sacred white elephant: the recipient could not refuse it, sell it, put it to work, or harm it, yet had to keep it impeccably — and the upkeep was financially crippling.
Source: Dicio.
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