1) Ancient 2) Ancient, to a poet 3) Ancient, to poets 4) Ancient; quaint 5) Antiquated 6) Bygone 7) Certain days 8) Days of yore 9) Days or times 10) From days of yore 11) From days past 12) From years past 13) Hardly modern 14) Immemorial 15) Like days gone by 16) Like days gone past 17) Like days in the past 1) Bygone 2) Of the past 3) Past 
Olden is a quasi-archaic English word meaning `old` or `ancient`, as in `olden days`. Olden may also refer to: ==Places== ==People== ==Entertainment== ...
• (v. i.) To grow old; to age. • (a.) Old; ancient; as, the olden time.
Old'en adjective Old; ancient; as, the olden time. 'A minstrel of the olden stamp.' J. C. Shairp. Old'en intransitive verb To grow old; to age. [ R.] « She had oldened in that time.» Thackeray. 
[adj] - of time long past
adjective long past; `olden days`