Metaphorically speaking

A metaphor turns one thing into another. Start with the statement:

A road is a road for cars.

and see how many roads (and paths and byways) you can come up with that carry something from one place to another.

• An artery is a road for exhausted blood leading back to the heart.
  
• The internet is a superhighway for spam.
  
• School is a potholed dull path to college that they've been promising to pave for decades.
  
• A river is snowmelt's road from mountain to ocean.
  
• Pretend is a road to anywhere.
  
• A lecture is a pathway to sleep.