If one were to go to the very beginning of this building's history you would actually start with what is now the clock tower.
A tall octagonal wooden fire lookout tower once stood on this site and was located in the center of Jefferson Market in 1833. Court sessions were held in the rooms built above the market which would soon be torn down to make room for a new courthouse and an adjacent jail building.
Originally built as the Third Judicial District Courthouse and designed by architect Frederick Clarke Withers, the Jefferson Market building would serve this purpose from 1877 to 1945. The courthouse saw a lot of action in its day, serving what was then known as "The Tenderloin" entertainment district.
After its decommission the building's future was in jeopardy. Luckily, a community preservationist, Margot Gayle, and writers like E. E. Cummings and Lewis Mumford rose to the challenge and formed the Committee to Get the Clock on Jefferson Market Courthouse Started which eventually got the New York Public Library to convert the disused courthouse into a library.
The library opened in 1967, entered the National Register of Historic Places in 1972, and was declared a National Landmark in 1977.