The Joseph Regenstein Library, often referred to by students as "The Reg", is the main library of the University of Chicago, named after the industrialist and philanthropist Joseph Regenstein. It is one of the largest repositories of books in the world and is noted for its brutalist architecture.

Brutalist architecture is an architectural style that emerged during the 1950s in the United Kingdom, among the reconstruction projects of the post-war era. Brutalist buildings are characterised by minimalist constructions that showcase the bare building materials and structural elements over decorative design. The style commonly makes use of exposed, unpainted concrete or brick, angular geometric shapes and a predominantly monochrome colour palette; other materials, such as steel, timber, and glass, are also featured.