On February 13th, 2022, AO3 made a news posts encouraging users to post their recommendations of "classic" fics, while acknowledging the definition of classic may vary from user-to-user. These were the fics recommended that day in the comment section.
About International Fanworks Day 2022 - Classic Fic Recs (IFDRecs)
* A fic's presence here is contingent on the author's AO3 settings and wishes. Authors can revoke the collection's permission at any time. The most comprehensive list will always be the original 47 pages worth of comments.
* Self-promos, offsite works, and orphaned/anonymous works are listed as bookmarks with the specifying tag.
I am a random user, not AO3 staff. This collection and account exist solely to collate those recs and make them sortable.