Fodor's Expert Review Library Hall

This 20th-century building is a reconstruction of Franklin's Library Company of Philadelphia, the first public library in the colonies. The American Philosophical Society, one of the country's leading institutions for the study of science, has its library here. The vaults contain such treasures as a copy of the Declaration of Independence handwritten by Thomas Jefferson, William Penn's 1701 Charter of Privileges, and journals from the Lewis and Clark expedition of 1803–06. The library's collection also includes first editions of Newton's Principia Mathematica, Franklin's Experiments and Observations, and Darwin's On the Origin of Species. The APS also offers a small, rotating exhibit of its rare books and manuscripts in the lobby of its first floor.