Morgan was most famous for her project on Sam Simeon, San Francisco for the Hearst family in 1919. The project included designing and building a pan-European styled castle, which was later to be known as the Hearst Castle. It was made of fragments of architecture from Italy and Spain. This project lasted for 25 years. Morgan’s architectural team also designed many houses, churches, cottages, schools, and many other types of buildings. Her biggest goal was always to satisfy her clients and “design buildings from the inside out.” She did so in styles anywhere from Byzantine, Italianate, Craftsman, Gothic, Romanesque, etc.