This concert on the Charles River Esplanade, begun by late Boston Pops conductor Arthur Fiedler in 1974, has become a nationally known holiday tradition. The evening's high point is the fireworks display over the Charles River, timed to begin just as the 1812 Overture reaches its climax. The Pops usually bring a roster of pop music and political stars to help inspire revelers with patriotic spirit. If you go, arrive early; people begin showing up a day in advance, and crowds can be as large as a half-million people. Admission is free.