Roman basilicas, for instance, are very large so they can accomodate many people, and a wide variety of occasions. A building such as St. Peter's in Rome can be deemed important due to the magnitude of the structure. Smaller buildings, such as residential houses, are lesser in stature as well as importance. The larger features of a stucture stand out as the most prominant. For example, the dome on the Pantheon is its main attraction, and thus occupies the largest area.
Proportion refers to the relationship of the parts to each other.
Symmetry - Symmetry describes the technique used to make one half of a building look like the other. This gives the structure order, and exudes stateliness. Examples of contrasting textures are smooth marble and rugged brick. It can dictate the mood and the purpose of a building. The addition of color has the ability to blend or contrast with a structure's more intricate details.