On May 31, Puerto Vallarta will mark 38 years as a city and 88 years as a municipality by staging a huge free concert. Featuring 11 bands playing a wide diversity of Mexican and Latin music including banda, norteno and cumbia, this event takes place at 8:30 pm on the Malecon in front of the Seashore statue, PV'S most internationally recognized tourist landmark. And when the music stops, the night sky will alight with fireworks. The celebration includes its more solemn aspects, the mayor presenting citizens who have made important contributions in the areas of art, culture, sports, social welfare, the ecology, education and tourism with 14-karat gold medals. That happens at City Hall at 7 pm. Then, at 8, 2,500 folks get to have a piece of Puerto Vallarta's huge anniversary cake.