In western Christian societies, beginning in the Middle Ages, cathedrals became a form of sacred construction which encoded subtle spiritual wisdom. They were built according to the age-old principles of sacred architecture, and were one of the finest artforms with the purpose of expressing the harmony of the universe. Each building as a whole was an image of God and Creation itself.
The principles of sacred architecture, upon which the cathedral construction and layout were based, drew from the mystical science and philosophy of Plato and Pythagoras, making extensive use of sacred geometrical ratios and patterns, such as the Golden Ratio (Phi) and the Flower of Life
The builders of such cathedrals were actually guilds of Freemasons, whose records indicate that their knowledge of sacred architecture and geometry had its origins in ancient Egypt. This tradition was extended by the Knights Templar, inspired by the Hermetic knowledge they had rediscovered in the Middle East.
Many cathedrals also incorporated hidden symbolism regarding the mysteries of Nature (for example, the Green Man) and sacred sexuality (the steeple and cross). The art of stained glass was also incorporated, using light, color, and spiritually-themed beauty to help tune the perception toward the divine. Some cathedrals also included labyrinths for walking meditation, based on the symbolism of the spiral, Axis Mundi, and the Unity of Life.
Sacred geometry is incorporated into a vast number of cathedrals and churches, but a particularly striking example exists in Chartres Cathedral (Cathédrale Notre-Dame de Chartres) in France. As can be seen on this page, sacred geometry can be found in the layout of the cathedral's ground plan, as well as its stained glass windows, which both contain the Phi ratio or Golden Mean. Additionally, the famous Labyrinth on the floor of the cathedral forms a perfect equilateral triangle with the rose window on the western wall, and as is demonstrated quite beautifully on this page, the labyrinth's design contains both the Golden Ratio and the Flower of Life. The cathedral was thus built according to the proportions of the building blocks of creation, said to stem from the Divine Mind, and in this manner, cultivated a harmonious and sacred locality.
Many cathedrals and churches were built upon former pagan sacred sites, which had often been previously marked by megaliths and other standing stones, which were placed upon ley lines. These sacred spots were often located upon intersections of ley lines, where the standing stones were erected as a means of guiding, focusing, and calibrating earth's energy grid, much like in the practice of acupuncture on the human body. Thus, cathedrals were a continuation of this tradition, serving to channel and enhance earth's natural energy flow toward spiritual growth, general well-being, and other productive outcomes. Chartres Cathedral itself was built upon the crossing of ley lines, forming a vortex or power center (much like an acupressure point on the human body), which is focused particularly intensely within the center of the Labyrinth - promoting healing and spiritual insight for those who enter this sacred space.
The steeples of Chartres and other cathedrals, which emphasize the connection between Heaven and Earth, are based on the Egyptian Obelisk, and are also reminiscent of acupuncture needles. Chartres' double steeple design also reflects the Two Pillars of the Tree of Life (integral to Kabbalah and Freemasonry), as well as the ida and pingala nadis within the human body. The cross found on all Christian churches harkens back to very ancient solar and Axis Mundi symbolism. Both of these symbols also encode the secret of Gnostic and Tantric sacred sex practices which lead to the enlightenment, healing, and salvation taught by Jesus Christ via the ascension of kundalini, the Serpent Fire. As such, cathedrals unify much of the world's spiritual wisdom within a single structure.