I didn't know till this year that you can actually climb up the outside of the O2 (used to be called the Millenium Dome), so when it proposed to me that the 2 friends and I should do this I was a bit nervous not being in the first flush of youth but I need not have worried because it was really good fun and not particularly arduous and obviously the views from the top of the dome were fabulous. The staff were very professional and made sure everyone was quite safe and enjoying themselves as well,. They told us that the oldest person that had done it was 93 years old so if you get the chance and fancy it don't hesitate and you will not be disappointed.