Fonthill Castle is a unique structure located in Doylestown, Pennsylvania. Built between 1908 and 1912 by Henry Chapman Mercer, the castle showcases a blend of Gothic, Byzantine, and Moorish architectural styles. It is made primarily of reinforced concrete and features intricate tile work, stained glass, and numerous rooms filled with artifacts. The castle served as both a residence and a museum for Mercer’s extensive collection of decorative arts and historical items. Today, it is part of the Mercer Museum and is open to the public for tours, allowing visitors to explore its fascinating design and rich history.