ago
Pronunciation: /əˈgəʊ/
adverb

Origin:
Middle English ago, agone, past participle of the obsolete verb ago 'pass', used to express passage of time

When ago is followed by a clause, the clause should be introduced by that rather than since, e.g. it was sixty years ago that I left this place (not it was sixty years ago since I left this place). The use of since is not correct in standard English.