Built as a summer retreat for the Kaufmann family, Fallingwater has been donned as Frank Lloyd Wright's greatest masterpiece. Unfortunately the house has suffered from structural deficiencies since its original construction. The main cantilevered terrace over the creek and waterfall, the trademark of the house, had deflected nearly 20 cm since the house's construction, and the deflection was ongoing. Structural cracks were also rampant throughout the terraces and the house. The repair of the house included external posttensioning of the inverted tee beams on the main cantilever. In cooperation with VSL, Robert Silman & Associates, and Schupack-Suarez, Penn State monitored the structure throughout the construction process. This paper will focus on the instrumentation of the historic structure as well as a comparison of the readings to the predicted values. The use of this structure as an educational tool for structural engineering students will also be discussed.