Throughout the Capitol building there are many areas of ornate stenciling, Greek keys, acanthus designs, and elaborate decorative elements that were artistically a statement of Joseph Huston's American Renaissance design. While other artists dealt with the fine arts and specific Pennsylvania topics, the decorative elements in the building were contracted to the Donald R. MacGregor firm of Philadelphia.

Donald MacGregor (1870–1930), the principal in the firm, studied art at the Pennsylvania Academy of the Fine Arts under William Merritt Chase. He in turn completed several murals within the building. A notable mural, entitled Venus and Two Loves, was painted on the ceiling of a room in the Lieutenant Governor's office suite, which in 1906 served as the Ladies Reception Room.

Additional murals that MacGregor produced are located at the light court ends of each hyphen corridor, entitled the Four Seasons. In addition the painters on MacGregor's staff were responsible for all the gold and aluminum leafing, stenciling and glazing work, and highly ornate decorative painting throughout the building — a truly massive undertaking. Without the creative work of the MacGregor firm, the beauty of the Capitol would not be unified with its architectural surroundings. Their work is a blending of all of the building's elements, creating a harmony of art.