Historical clue formulations

• Each of its interior angles measures 135° — 2022-07-10
• Stop sign shape — 2019-04-17
• Shape of a stop sign — 2016-03-28
• Figure seen at an intersection — 2004-05-27
• ___ Building, landmark on New York's Roosevelt Island — 2002-10-20
• Unusual house shape — 1997-10-19