The Spiral Stairs

I remember once seeing a shot of this many many moons ago and on my recent trip to rome went to Vatican Museum and searched everywhere for the 'spiral staircase'! 5 hours later nothing....

I thought it had eluded me and I gave up, we had other things to look at and went to leave..... And there I found it! It's part of the exit! Felt a right fool but was left leaving with a smile on my face!