The idea of the American library was born in Philadelphia in the eighteenth century. Since then, this has been a place of sustained innovation by architects and clients who have created buildings that do more than facilitate access to books. The University of Pennsylvania Library, opened in 1891, was conceived by architect Frank Furness and his brother and library committee chair Horace Howard Furness as an embodiment of the unstoppable spirit of the nation’s largest manufacturing city. The central branch of the Free Library was designed by Julian Abele, the first African American graduate of Penn’s architecture program. Completed in 1927, it was part of the effort by a remarkable group of civic leaders to undo the work of the previous generation and transform the industrial metropolis into a center of culture and commerce. And when the library of Phillips Exeter Academy opened in 1972, Philadelphia’s Louis Kahn (working with long-serving librarian Rodney Armstrong) put on display the new direction for modern architecture that had been born in this city. Eschewing generalizing abstraction and mere functionalism, he made a library that moved books—and their readers—to the light.