Fallingwater's horizontal and vertical lines are some of the distinctive features of what has come to be called the International Style. Math and science combine to make this one of the most interesting residences of the twentieth century. Believe it or not all these perpendicular lines, parallel lines and intersecting lines make visible polygons in the form of living space. On the main level of Fallingwater the perimeter of the rectangular central space is lit by square ceiling panels. The four corners are supported by rectangular patterned stone piers.
The cantilevered roofs and terraces create planes and rectangular prisms that seem to go on and on. It is this quality that makes Frank Lloyd Wright's homes look like they are a part of the landscapes. Fallingwater was made from the geometric order that Frank Lloyd Wright saw in the uneven rocks and made the rectangular slabs regular rectangles. Frank Lloyd Wright found the way to Fallingwater was through the natural environment of Bear Run, Pennsylvania. Fallingwater's horizontal lines go up to three levels with rectangular and parallel terraces and cantilevers over the  rocky bank. The horizontal bands, that are made of concrete, are balanced by a perpendicular wall.

 http://www.psu.edu/ur/archives/intercom_1997/tour/fallingwater.GIF
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