Ancient city fortifications are one of the specific types of defensive architecture. Along with the buildings of castles, blocks of urban residential development, monastery complexes and field defensive structures, they formed a special type of architectural and urban planning objects. During their construction, the skills of both an architect, builder, and military engineer were often combined. Not so many objects of urban defense architecture have come down to our time. Therefore, every fragment of the city's defensive walls and earthen fortifications preserved today, as a rule, is a valuable document of its era and needs careful protection and preservation. Urban fortifications (as opposed to fortifications of castles or fortresses) were the objects of priority liquidation in the process of urban development. There are very few of them preserved in Ukraine, so their preservation and study is a matter of extreme importance. Lviv is a unique city on the map of Ukraine in terms of the development of urban fortifications. The article analyzes the reflection of objects and monuments of defense construction in the scientific and design documentation "Historical and Architectural Reference Plan of the City of Lviv". Data on the stages of development of Lviv fortifications are highlighted. Special attention is paid to the remains of fortifications that have been preserved in the archaeological form. Their identification, conservation and identification is important task for modern urban development projects. The paper makes hypotheses about some hitherto unidentified elements of fortifications of the XVII-XVIII centuries. Special emphasis is placed on the need for a special scientific study on the detailed reconstruction of all stages of the development of defense belts around the city center and suburbs of Lviv