Related Clues:

• Centuries and centuries
• Slice of history
• Time period
• A long, long time
• Stretch of history
• Immeasurable period
• Loooong wait
• Forever, seemingly
• Many a moon
• Clock watcher's wait, seemingly
• Endless years
• A lo-o-ong time
• Two or more eras
• Very long stretch
• Geologist's measure