Stairs are name for a construction designed to bridge a large vertical distance by dividing it into smaller vertical distances, called steps. Stairways may be straight, round, or may consist of two or more straight pieces connected at angles.

1.Australia
Spiral Stair at Garvan Institute

2.Italy
Spiral Staircase at the Vatican Museum
3.USA
Loretto Chapel Staircase
4.England
Tulip Staircase at the Queen's House
5.Portugal
Staircase at Lello Bookshop
6.USA
San Francisco's Tiled Steps - World's Longest Mosaic Stair
7.Germany
"Umschreibung" at KPMG Building Munich
8.New York
Stairs at the Longchamp Store
9.Australia
Vertigo Staircase at the QVB Building
10.Switzerland
Bridge-stair at the Traversinertobel

So how ? Cool ,isn't it ?
But overall I like the stair no.2 that is "Spiral Staircase at the Vatican Museum" because it is simple and elegant. How about you ? Let me know in the comment below.