Historical clue formulations

• Abbr. before a year on a business sign — 2023-10-23
• Abbr. before a date on a business shingle — 2021-11-22
• Business sign abbr. — 2020-07-08
• Cornerstone abbr. — 2019-12-01
• Cornerstone abbr. — 2018-12-02
• Founded: Abbr. — 2018-06-27
• Business sign abbr. — 2017-12-02
• Founded: Abbr. — 2015-07-29
• Sign abbr. meaning "founded in" — 2010-03-02
• Foundation abbr. — 2009-12-16
• Business sign abbr. — 2009-03-25
• Founded: Abbr. — 2008-05-22
• Cornerstone abbr. — 2003-06-15
• Instituted: Abbr. — 2002-05-25
• Abbr. on a college building — 2001-02-18
• Cornerstone abbr. — 2000-03-30
• Tavern sign abbr. — 2000-01-09
• Cornerstone abbr. — 1997-08-17
• Founded: Abbr. — 1996-04-07