Tall As A House


What is as tall as a house and round as a cup,
yet all the kings horses could not draw it all up?
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   |
   v
Answer:
A Well.