The answer to this question is difficult to determine as there are many factors to consider. For example, the size of the venue, the popularity of the artist, and even the location of the concert can all affect how many people attend. Additionally, it is hard to compare crowds at different concerts as there is no standard way to measure them. However, based on available information, it seems that U2 holds the record for the largest crowd at a concert.
In 2009, U2 performed in front of an estimated 3.5 million people at Copacabana Beach in Rio de Janeiro as part of their 360Â° Tour. This was not only one of the largest crowds ever assembled for a concert, but also one of the most diverse; with people from all over Brazil and other parts of South America coming together to watch Bono and company perform hits like "Where The Streets Have No Name" and "I Still Haven't Found What I'm Looking For."
While U2 may have had the biggest crowd at a single concert event, they are not necessarily responsible for drawingthe largest overall audience over multiple shows. That distinction goes to The Rolling Stones who played 82 concerts during their 2005-2007 Bigger Bang Tour which was seen by an estimated 4.6 million fans worldwide. And while Madonna may not have drawn quite as many total attendees as The Stones did on their tour (an estimated 3 million), she does hold claim to having played before more paying customers than any other solo artist; grossing $1 billion dollars from her 2008-2009 Sticky & Sweet Tour which spanned across 32 countries and four continents over 85 shows.