An important role in the formation of the architectural style of Lviv was played by the beginning of the twentieth century. As the capital of Galicia, which at that time belonged politically to the Austrian Empire, Lviv was strongly influenced by the Austrian Secession and the head of the Vienna School of Architecture O. Wagner. Nevertheless, Lviv architecture, to a certain extent, has preserved its originality and uniqueness. Secession is a phenomenon of the Lviv architecture of the early twentieth century. It determines the definition of sculptural decor as one of the main components of the “newest” artistic image of a building. Among the various types of plastic decoration, an important place is occupied by relief masks – mascarons, which are the most mysterious, attractive, and bizarre elements of the architecture of the Lviv Secession. The article notes the influence of various factors on the formation of new typological groups of mascarons not found in the architecture of previous eras. The artistic images of secession arise at the intersection of two key symbols and constant themes of art nouveau – eternal femininity and fabulous nature. In almost all cases, female mascarons are accompanied by plant motifs of the local flora.