Travel Trivia: Where is the steepest-sloped street in the world?

 I'll guess C. Baldwin Street.

C. 

C

 C

c.  Baldwin Street, New Zealand

 C. New Zealand

Waipi'o Valley Road, Hawaii. USA.

Having experienced the down and back up, plus the condition of the road, I'll attest to it. 

That said, it's worth it!

C, New Zealand 

c.  Baldwin Street, New Zealand

C. Baldwin St., New Zealand