Stand in the center of Beijing's Temple of Heaven and look around. You're standing on a circular platform. That circle represents heaven. The platform sits atop a square base. That square represents earth.

The entire structure is a cosmology lesson in stone. Heaven is round. Earth is square. Where you're standing, at the intersection, is where the emperor performed rituals to keep heaven and earth in harmony.

This isn't unique to China. Across cultures, sacred architecture encodes cosmology in the floor plan. Temples, churches, and mosques are maps of the universe, teaching believers about the structure of reality just by walking through the space.