Rome wasn't built in a day.

‘罗马不是一天造成’英文叫Rome wasn't built in a day。这个绝对是当然的，想要有坚固的后盾和实力，千万不可一步登天，何况上帝造人也要六天时间。所以凡事都不可操之过急，要慢慢来，It won't happen overnight.（这不会一夜间发生），或者你可叫朋友Slow down.（慢慢来）、 Be patient.（有耐性）、What's your hurry?（你在赶什么？）。
对话
A: What's up? You look really down.
B: I'm so tired of my job. There are endless problems to deal with.
A: Be patient darling. Rome wasn't built in a day.
B: Yes, I know. Thanks for your support.
甲：什么事？你看来心情很差。
乙：我很厌倦我的工作，总有无尽的问题要处理。
甲：忍耐点，爱人，罗马不是一天造成。
乙：我知道，谢谢你的支持。

英文不少成语谈到古罗马。All roads lead to Rome.（条条道路通罗马）一语，等于‘殊途同归’，经翻译后流行得几乎已可说是中文成语。

Rome was not built in a / one day.（罗马不是一天建成的）是另一常见的成语，有‘锲而不舍，金石可镂’的意思；做事延误了时间，也往往用这句话辩解，例如："Haven't you finished writing the report yet?" "It'll take some more time. Rome wasn't built in a day, you know."（‘你还未写好那份报告吗？’‘这要多点时间。想做好一件事，可不能求快。’）

和Rome was not built in a day. 意思相近的英文成语，有It's dogged that does it。Dogged是形容词，指‘顽强的’或‘固执的’，例如：The reporters asked him doggedly about his role in the scandal.（记者锲而不舍，追问他在丑闻中的一切）。I'm sure you will master the English language one day. It's dogged that does it. 即‘我相信有一天你会精通英文。只要功夫深，铁杵磨成针’。

此外还有to fiddle while Rome burns（罗马大火时弹琴作乐）一语。据说，罗马暴君尼罗 (Nero) 曾经纵火焚城，一边观火一边弹小提琴 (fiddle)。现在这句话常用来说不理民间灾难的官员。