Historical clue formulations

• Some steel beams — 2023-03-12
• Parts of many skyscrapers — 2022-05-01
• Some building beams — 2020-07-28
• Certain building beams — 2020-04-08
• Construction girders — 2019-06-30
• Some beams — 2018-07-22
• Some girders — 2018-07-08
• Some support beams — 2014-01-02
• Reinforcement pieces — 2013-10-05
• Letter-shaped construction pieces — 2011-12-19
• Bridge supports — 2009-12-12
• Letter-shaped construction pieces — 2009-10-18
• Building beams — 2009-05-06
• Some beams — 2008-02-21
• Certain supports — 2005-12-04
• Tower supports — 2005-01-02
• Building supports — 2004-10-10
• Support group? — 2003-03-15
• Struts used in gratings — 2002-09-01
• Building supports — 2001-09-13
• Some supporters — 2000-09-30
• Bridge-builders' beams — 2000-04-19
• Certain girders — 1999-05-30