This collection contains over four thousand color slides and black and white photographs of medieval Spain taken by the late Eugene Casselman (1912-1996) during his thirty years of travel throughout the Iberian peninsula. The images span over one thousand years of architectural history, from the seventh to the seventeenth century. The majority of the slides focus on the Mudejar style, an ornate court style largely inspired by Spanish Islamic architecture that was shared among Islamic, Jewish, and Christian cultures during the later Middle Ages in Spain. He even began writing a book-length manuscript on Mudejar architecture, which he never completed.

One of the collection's greatest strengths is its breadth, which enables the viewer to see the deep-rooted influence of Islamic art and architecture in Spain. Mosques were consecrated as churches, minarets became bell towers, and Muslim palaces became the residences of the Christian kings, all contributing to the affinity for Islamic tastes and techniques. Muslim masters worked for and with Christians and Jews to create these architectural masterpieces in brick, timber, and stucco. The late Middle Ages in Spain is characterized by the co-existence of these three cultures, known as the Convivencia.

Eugene Casselman was born in Japan to missionary parents and studied voice and music history at Tiffin University (Ohio) and Westminster Choir College (Princeton, NJ) and received his master's degree from the American Conservatory of Music (Chicago, Illinois). He taught voice and music history at Gustavus Adolphus College (Red Wing, MN), Colorado Technical College (Colorado Springs, CO), Downer College (Milwaukee, WI), and Lawrence University (Appleton, WI). His other passion was the architecture of medieval Spain and photography. He exhibited some of the photographs from this collection in 1983 at the then Elvehjem Museum of Art. The slides and photographs were donated to the Department of Art History by Eugene Casselman's widow, Frances, and his children.

Special thanks are owed to Richard Busby for his efforts at organizing, describing and scanning the 4,000 images that form this unique collection. Richard Busby, who completed his Masters in Art History at UW-Madison in the summer of 2007, is currently a PhD student at Emory University in Atlanta studying late-medieval Italian art. He is particularly interested in funerary chapels and the themes of resurrection and memory, investigating the ways in which patrons sought to commemorate themselves and their families through artistic commissions.