In many sport events, the size of the playing field is uniform. For example, American football is played in a rectangular field of dimensions 120 yards by 53.3 yards and the size of a professional basketball (NBA) game is 94 by 50 feet. Although the layout of the infield is the same for all Major League Baseball parks, there are notable differences in the physical dimensions of the outfield. In addition, there are many variables that influence the path of the home run such as the distance to the fence, the wind and temperature conditions, and the altitude of the park. We begin this chapter on batted balls by exploring the variability in the number of home runs hit in the 30 MLB ballparks.