English version

red-letter day

From Longman Dictionary of Contemporary Englishred-letter dayˌred-ˈletter day noun [countable]  informal a day that you will always remember because something special happened that made you very happy
Examples from the Corpus
red-letter dayIt is also a red-letter day for Bath's Ben Clarke, who makes his debut.It could mean the difference between a red-letter day and an empty basket.August 17 was a red-letter day because at last the dorado-catching campaign succeeded.This was a red-letter day indeed.Finally the couple may be celebrating a birthday, a wedding anniversary or some other red-letter day.
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