This isn’t for the faint hearted, the climb to the top is very difficult! Although you can get a lift the most of the way for an extra €2 I felt it was well worth taking in the complete experience and taking a walk to the top.
Once you reach where the lift can take you, there is the another climb, this time up a very steep, 1 person wide alley way with a slight lean to the right. It does make you feel quite claustrophobic!
Once you have overcome the hike, the views are breathtaking - well worth the climb and aching legs/feet.
I would also recommend doing this very early morning or very last admission. I went for pretty much first admission with hardly any queue and without hundreds of people on the stairs at once.