Definitely worth the hike up all those stairs for the stunning view of the city you receive at the top! I believe I paid about £5 per person, so it's fairly affordable. Be warned, however. There is a fair amount of steps and the stairway gets much narrower as you get higher up, and the last 10-15 steps are a tight fit. If you're claustrophobic I would suggest otherwise, but as a friend of mine who was 6'1" just barely fit