The Oscar-winning actress purchased the land above and around a waterfall in rural California for the actor`s 48th birthday last month.
Budding architect Brad - who raises six children with Angelina - now plans recreate his hero Frank Lloyd Wright`s famous Pennsylvanian Fallingwater estate.
A source told the New York Post newspaper: "Brad has always loved Fallingwater and his first trip there was unforgettable. Angelina wanted to get him something incredibly special and, because she knows how much he loves architecture, she thought this would be perfect.
"She hopes this will be a hideaway for the family. Brad has dreamed of a home with the sound of a waterfall cascading under the house.
"Brad has always wanted to design his own house. He wants to pull all aspects of nature, light, glass and varying levels into the concept. This is the present to top all presents."
And it seems Brad may have to make extra room in the house as Angelina recently revealed she could have another child.
When asked whether she wants to expand her brood, she said: "Nothing is planned at the moment, but we just don`t know. I could end up pregnant."