O2 Arena 2009 was obviously sold out, was this a proper general admission standing gig, or seated? I fear the latter, then it was 20,000. The standing capacity would be 23,000. It's on the O2 site. Although I've been there myself and it's hard to believe the difference between seats on the field and standing tickets would be only 3,000, this is the most accurate information you can get. EDIT: tickets available for the same venue in 2011 were
16,225. Source:
http://www.webcitation.org/query?id=1327995081254957&date=@0&fromform=1 2) "near sell-out", "a crowd of nearly 60,000" (
http://www.walesonline.co.uk/news/wales-news/sir-paul-mccartney-wows-millennium-1915251)) Capacity must be around 73,354, the number U2 played for, and which is the highest music concert audience the stadium ever had.