The more borders fall, the greater the academic interest—not only in historical sciences—in all kinds of borders; here, borders are understood not only as those between territories but also those between languages, confessions, genders, political and economic systems. This seemingly paradoxical phenomenon is also addressed in Volume 67 of the RHM titled "Crossing the Border. Illicit crossings, controls, strategies (16th-19th centuries)." It focuses on territorial borders, which are understood primarily as political constructions, as well as their illegal crossings, critically questioning the problematic term of illegality from the editors' perspective. A total of thirteen case studies revolve around these themes, covering various European regions from the Early Modern period to the early 20th century. The individual contributions discuss, on one hand, a specific group of people who frequently crossed borders, and on the other hand, goods, animals, or epidemic diseases. The monitoring of borders has always been in the tension between theoretically comprehensive legislative provisions and practical limitations in their implementation. Individuals who violated borders, others whose task was to control the borders, and yet others who collaborated in one direction or another are—not always clearly separable from each other, often in stark contrast to the intentions of the legislation—as the editors Francesca Brunet and Siglinde Clementi pointedly note.