Roswell P. Flower Memorial Library is a historic library building located at Watertown in Jefferson County, New York. It was built in 1903 and is a two story, brick, rectangular building faced in marble with a centrally placed octagonal dome. The dome creates a three story octagonal rotunda, which is the principle interior feature. It was erected as a memorial to Watertown's most prominent son, Roswell P. Flower (1835–1899).It was listed on the National Register of Historic Places in 1980.
