Straight lines are the basis of many architectural and engineering principles. Look at all of the roadways and buildings that man has constructed. Straight lines are easier to build than curved ones. Straight lines are also very efficient. For example, cubes with straight lines are easier to transport in bulk and to construct things with then spheres. Straight roads are easier to drive on and result in less energy use when compared to a curved roadway. Straight lines also make up one of the strongest shapes used in the engineering world, triangles. In engineering, straight lines enable designers to control and direct forces such that the things we invent perform at their desired level of functionality. In addition, you've probably heard the saying that the shortest distance between any two points is a straight line. This is certainly true within the context of any finite three-dimensional space.