The festival goers stay in a hughe tent camp, and is infamous for its muddy fields when it rains. Despite the mud, the festival is as popular as ever, and tickets can be difficult to get. Half a dozen other festivals are held around the country, mostly in rural areas. An old pagan ritual, that is very much alive, is to have bonfires at the summer solstice. This was done to christianize the holiday, much the same way chistmas was put around winter solstice.
Some bonfires also have an effigy of a witch on a broomstick on top of the fire.
The effect is sometimes enhanced by putting some fireworks inside the effigy. Folklore says that if such a party is not held, the building will have problems later on. And when even modern Danish buildings are made to last a century or more, better be on the safe side. Of course, it has probably happened that if such a party was not held, the workers would do poor work, or even sabotage it. One of my parents old neighbors, who is a carpenter, told the story about a house in the area, where he could see the workmanship was done poorly on a couple of the trusses.