Last weekend Madonna performed the biggest ever concert by a solo artist, with an audience in excess of 1.6M on Rio’s Copacabana beach. The concert was free and rounded off her 81 date Celebration Tour, which grossed a reported $77.4M. So why did Madonna perform a free gig, when she could have made even more money and consolidated her status as one of the highest grossing touring artists ever? Madonna has always known how to market herself, long before the days of the internet.