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Rome wasn't built in a day.
Literal
Rome [topic-は] one day [as-にして] become-not [archaic-form-ず].
A famous proverb (ことわざ) — the Japanese rendering of the European proverb 'Rome wasn't built in a day.' Uses archaic/literary grammar: にして as a formal connector ('in/on'), 成らず as the classical/文語 negative form (現代 equivalent: 成らない). Common in proverbs and set phrases that retain their archaic formulation. Used to remind oneself or others that great things require time.