Photos courtesy of J.L. Robinson Inc., Pittsburgh.

To prevent Fallingwater from sagging farther, three of four 36- by 20-inch (914- by 508-mm) concrete beams were strengthened with a post-tensioning system. To do this, steel cables were placed along each side of the beams. One end of the cables was anchored in new concrete blocks attached to beams, and the other fed through holes drilled through the outside living room wall. Hydraulic jacks gradually tightened the cables.

Visitor tours continued during renovation work at Fallingwater.

Fallingwater, which mimics the area's rock ledges' natural patterns, is designed as a series of cantilevers, or supporting shelves.

System mock-ups were prepared to show the materials being installed on Fallingwater's terraces and roof systems.

Fallingwater flows with Wright's concept of organic architecture, the harmonious union of art with nature.

This Web exclusive information is a supplement to Doing it better than Wright.