Lollapalooza (Lolla) is an annual American four-day music festival held in Grant Park in Chicago. It originally started as a touring event in 1991, and many years later, Chicago became its permanent location. Music genres include alternative rock, heavy metal, punk rock, hip hop, and electronic dance music. Lollapalooza has also featured visual arts, nonprofit organizations, and political organizations. The festival hosts an estimated 400,000 people each July and sells out annually. Lollapalooza is one of the largest music festivals in the world and one of the longest-running in the United States.