How can I create a staircase that brings you down to your original position

I don’t really know how to explain it, nor what it called, but the basic premise of what I want to create is a staircase inside of a building, and when you go up or down it, you end up where you originally began.
Here is a crude diagram to explain what I mean:

What I want to know is:

  • What is it called
  • How I could go about making it look convincing