Adam-Federal house plans have their origins in the classical formality of the post-colonial period. Noted for its simplicity, symmetry, and grace, the style evolved from the work of English architect Robert Adam. Adam-Federal floor plans are generally rectangular or square, with two or three stories under a side-gable or hipped roof. Commonly built of brick, they may also feature clapboard siding. Their most distinctive feature is their symmetry: Adam-Federal home designs feature either one or two columns of windows on either side of a central door, which is accented by a fanlight and pediment or a more elaborate one-story portico. There may be a three-part or Palladian window above the door on the second floor.