Related Clues:

• Key times, historically
• Many of them are named for monarchs
• Baroque and Classical
• Big Band and Swing
• Geologist's ten
• Meaningful spans
• Aces have low ones, briefly
• Often-named stretches
• Historic blocks
• Common and Christian
• Stretches in history
• Significant chunks of time
• Gaslight and Big Band, for two
• Stats for hurlers
• Notable parts of history