Fonthill Castle in Doylestown, Pennsylvania is a National Historic Landmark built between 1908 and 1912 by Henry Chapman Mercer, an archaeologist and tilemaker. The 44-room mansion showcases an eclectic blend of Medieval, Gothic, and Byzantine architectural styles constructed from poured reinforced concrete, an innovative building material for its time. Every surface—walls, floors, and ceilings—is adorned with handcrafted Moravian tiles from the American Arts and Crafts Movement, making it a unique showcase of decorative tile artistry that Mercer designed to preserve for future generations.