The Pioneer Memorial Library is located at 115 W. Main Street, Fredericksburg, Gillespie County, in the U.S. state of Texas. Designed by Alfred Giles, it was built in 1882 to replace the original 1855 courthouse, and was later superseded by the current 1939 courthouse designed by Edward Stein. The first floor houses the Children's Section, while the second floor houses the Adult Section, Texas Room, and newspapers and magazines. It is also called the McDermott Building because of the 1967 and 1984 restorations funded by Mr. & Mrs. Eugene McDermott. It was added to the National Register of Historic Places in 1971, and was designated a Recorded Texas Historic Landmark in 1967.

Alfred Giles was a British architect who emigrated to the United States in 1873 at the age of 20. Many of the private homes and public buildings designed by Giles are on the National Register of Historic Places and have been designated Recorded Texas Historic Landmarks. Based in San Antonio, his buildings can be found predominantly in south Texas and northern Mexico. Giles is credited with "a profound influence on architecture in San Antonio."