This is called a Swedish flame. Make your cuts like you're cutting cake, leave about 6 inches at the base, throw about a cap full of fuel oil in it. It burns up to two to three hours Can use olive oil instead of fuel oil :-) Any oil will burn!
Some people call it vandalism; the rest of the world unstoppable Urban Art, one day giant mural will decorate our cities. All our buildings will be covered because, as we all know, there is no earth without art.