In a Palladian window, a big arched window is flanked by two smaller sidelights. The window panes most often have square or rectangle-shaped grilles with more curvature at the arch. Historically, Palladian windows are more ornamental, including pillars between windows and entablatures above the sidelights.

Palladian windows are most common in public buildings and wealthy homes. Because glass was very expensive in the eighteenth century, the windows were designed with a larger glass area than regular windows. They can be found in many different types of architecture. For example, the Independence Hall in Philadelphia has a magnificent Palladian window in the center of the second story. Despite their size, Palladian windows are usually paired with other, more modern windows.