According to Official Guinness Records,
A free concert staged by rock superstar Rod Stewart (UK) at Copacabana Beach, Rio de Janeiro, Brazil, on New Year’s Eve 1994 reportedly attracted an audience of 4.2 million, although this figure is believed to include those who turned up solely for the fireworks display at midnight.
For a complete list of 1994 records, please visit 1994 Guinness Records in Brazil.