MILL RUN, Pa. —  Brad Pitt and Angelina Jolie visited Fallingwater, Frank Lloyd Wright's architectural masterpiece, where they celebrated the actor's upcoming birthday, Fallingwater's curator of education said.

The unique home spans Mill Run, a creek that flows through woods about 50 miles southeast of Pittsburgh. Wright built the home for department store magnate Edgar Kaufmann Sr. in the 1930s. The American Institute of Architects voted it the "Building of the 20th Century."

"Brad said he had wanted to experience Fallingwater ever since he took an architectural history course in college," said curator Cara Armstrong. "He and I talked quite a bit about design and art. He was incredibly well-informed about architecture."

Click here for more news on Brad Pitt.

Armstrong said she led Pitt and Jolie on a two-hour tour Thursday that was followed by a private birthday celebration for Pitt in Fallingwater's living room. The actor will be 43 on Dec. 18.

"Brad said he had a visual sense of Fallingwater but experiencing it in person, hearing the sound of the waterfall cascading under the house and smelling the wood from the fireplace, was better than anything he could have imagined," Armstrong said.

Pitt's new movie, "Babel," from Paramount Vantage, is now in theaters. Jolie, 31, has been filming "A Mighty Heart," based on a memoir written by Mariane Pearl, the widow of slain journalist Daniel Pearl.

Jolie's new film, "The Good Shepherd," will be released by Universal on Dec. 22.

Click here for more news on Angelina Jolie.