Situated at the center of the world's largest museum complex, the Smithsonian Institution Libraries links the holdings of 22 Smithsonian museums and research centres into one system encompassing 1.5 million books and manuscripts. The expansive collection includes many rare and unusual works equal to the celebrated art and artifacts of the Smithsonian's museums. This illustrated accompaniment to a new Smithsonian Libraries exhibition of the same name provides a three-part expedition through the collection. The first presents works such as a 1511 edition of Ptolemy's Liber geographiae (Book of Geography) and the pop-up book Buck Rogers, 25th century, featuring Buddy and Allura in Strange Adventures in the Spider Ship to illustrate how the world has been imagined, seen, and recorded by Europeans and Americans. The second journey explores how scientists have extended our understanding of the world, and includes a 1641 edition of Galileo's Systema cosmicum (System of the world) and a copy of Walden inscribed by Henry David Thoreau to Spencer Baird, then assistant secretary of the newly founded Smithsonian Institution.