In this article, the authors considered the development of Rashkiv (Raszków in Polish and Raşcov in Rumunian), the fortified settlement which is situated on the Middle part of the Lower Dnister Region. An attempt of reconstruction of the most important stages of its town-planning biography of the 15th-18th centuries was made. The authors based their research on newly identified sources. The systematization of the historical chronology of the most important events which have influenced the formation of the defensive structures and the urban environment of Rashkiv has been carried out. In the course of the 15th-18th centuries, four major urban planning periods were identified: the Lithuanian – fort Karaul in the form of a defensive roundel type castle, further – Zamoyski’s town fortress with a fortified downtown, then – the fortifying of the suburbs and, finally, – trade and handicraft town without any defense function. At each stage, an attempt was made to hypothetically localize separate elements of the city – fortifications, historical roads, street planning system, civil and sacral dominant elements. The authors all available source data – archival sources, historical and contemporary cartography, toponymics, field surveys, surveys, and iconographic materials for analysis.