Wharton co-wrote The Decoration of Houses with architect Ogden Codman at a crucial moment in design history. In 1897, when the book came out, America was desperately trying to rid itself of Victorian clutter but didn't know how. Treatises like Wharton's, advocating common-sense living and a return to simplicity, guided the way. That her version of simplicity was very different from ours—lots of "clean-lined" French furniture—is beside the point. By combining the best of European classical design elements and arguing for proportion and symmetry, Wharton contributed to a new American visual vocabulary and influenced a generation of tastemakers.

In 1901, she hired Codman to help her realize her own example of this vision: a grand, 42-room "cottage" overlooking a peaceful lake in Lenox, Mass., where she and her husband, Teddy, summered. (The rest of the year they lived on Park Avenue or traveled.) The Mount is more than a famous author's one-time summer home. It is a wood-and-stucco manifestation of Wharton's design principles and has the distinction of being an "autobiographical house."