While this book is primarily about places to visit where the history of the atom is celebrated, the reader will more fully appreciate these sites when it becomes clear that humankind only slowly and haltingly unraveled these atomic insights. Readers will come to see or be reminded that the pathway to the modern atom is one characterized by ingenious experiments and clear-headed observations as well as serendipitous accidents and irrelevant or ill-conceived manipulations; by great insights as well as wrong-headed ideas; by persuasive arguments by humble men and women as well as pig-headed opinions driven by big egos; by logical discussions, papers, and meetings as well as by personal attacks, stinging diatribes and heated debates.  This book relates some of these fascinating stories behind the development of the atomic concept.  For the scientifically literate, the background it provides will serve to jog the memory and remind us of what we might have recently studied in school or perhaps what we read or studied a number of years ago.  For others not so familiar with the history of the atom, it will provide enough of a framework to better understand the significance of a given site, experiment, person or piece of equipment.  This book, then, is about two types of landmarks – the temporal landmarks of the history of the atomic concept and the physical landmarks that have been preserved all over the European continent to commemorate this achievement.