South Physics Building
- Completed: 1967
- Named for: James C. Fletcher, President 1964-1971
- Architect: ??
- Style: ??
- Materials: ??
The Widtsoe building was originally the Physical Science Building. In 1976, this building was remodeled to house the Mathematics Department. Dr. Widtsoe was the author of the laws and by-laws of the first University Constitution.
This building was nearly destroyed by fire on December 19, 1901. but was restored in 1902. In 1911 an addition was constructed on the north side. The interior was remodeled extensively in 1975. This building differs greatly from its companion, the Alfred C. Emery Building, with a non-monumental entrance placed asymmetrically on its facade.