The Industrial Revolution and Enlightenment led to radical changes throughout the world in the late 18th century. New building materials like cast iron, steel, and glass allowed for larger structures. The Enlightenment promoted rational and scientific thought. In the late 18th century, Neoclassical architecture became popular, taking inspiration from Greek and Roman designs. This style emphasized symmetry, columns, and paying homage to classical prototypes. By the mid-19th century, the negative effects of the Industrial Revolution prompted a revival of classical architecture to beautify new industrial developments.