In 1850, Molnar as a citizen of Novi Sad raises his house on Trifković Square that exists today. Already in the first decade after the uprising, Molnar has built dozens of rise and storey houses in the city center. Molnar will raise several important urban facilities: hospitals (1867-1871), Serbian elementary school (1871-1874), Civic Hall, the first building of the SNP (1871), the City slaughterhouse (1882). Today there is only Miletićeva school in the churchyard of Nikolajevska Church. During the last decade of the nineteenth century Molnar designed and built his lives' work, also the most valuable urban buildings from the end of the century: the City Hall (1893-1895) and the Catholic Church (1892-1895). Both buildings were built in ornate eclectic style; Townhouse in Neo-Renaissance and the Catholic Church in neo-Gothic style. Molnar was, among other things, co-owner of the factory for production of building materials, longtime president of the Novi Sad Craft Association and a member of several committees for the building. His buildings are characterized by solid technical performance and simple, eclectic style, typical of the architecture of the southern provinces.