Related Clues:

• Yellows or grays
• Stretches of history
• Improves, as whiskey
• Nears retirement
• Important periods
• They may be checked at the door
• Almost eternity
• Millennia on end
• Bronze and Iron, e.g.
• Ever so long
• Becomes drinkable, perhaps
• Grows old gracefully
• Geologic divisions
• Iron and Bronze, e.g.
• Major time periods