Historical clue formulations

• Roman square — 2010-11-21
• Its dome was designed by Michelangelo — 2008-04-25
• Cardinals' gathering place — 2007-08-31
• Tourist site in Rome — 2005-04-16
• Workplace for Michelangelo — 2004-10-17
• Where Charlemagne was crowned — 1995-12-09