The Dana–Thomas House in Springfield, Illinois, was designed by Frank Lloyd Wright for Susan Lawrence Dana and built between 1902 and 1904, evolving from a remodeling of her Italianate mansion into one of his most complete domestic designs. Shaped by Wright’s organic architecture and a shared admiration for Japanese art, the house features expanding interior space, extensive art glass, custom white oak furniture, and rooms designed for entertaining and display. After Dana left it vacant, Charles C. Thomas and Nanette Thomas preserved the house and its furnishings. Acquired by Illinois in 1981 and restored from 1987 to 1990, it remains one of the nation’s most intact Wright interiors.