For nearly 20 years, the author, Mary Virginia Orna has led Science History tours to Europe and other parts of the world. Given the broad popularity of her tours among those in the scientific community, the ACS initiated a symposium on the topic as well as this book. The goals of both the Orna-led tours and this book include learning science through travel to sites where the science actually happened and describing how such travel can interface with the professional goals of chemists in academe, industry, and other areas of endeavor. This book makes it possible to plan a scientifically-oriented visit to well-known scientific sites armed with information not necessarily available on the internet or in guidebooks.