During the Roman Empire, roads were built to for trade communications: one of the branches, which took over the Alps, was called Via Sucinaria Romana and it reached the south-east coast of the Baltic Sea, where the Balts’ tribes lived. In the 13th century German knights subjugated the areas populated by the Balts’ and founded regular planned cities, borrowing urban planning skills from Romans. On March 5, 1562 during the Livonian War the Duchy of Courland and Semigallia (Latin: Ducatus Curlandiae et Semigallia; 1562–1795), subjugated to the Kingdom of Poland, was founded. Layouts of the capital city Mitau (now Jelgava) and residence towns Bauska and Friedrichstadt (now Jaunjelgava) were made in Renaissance traditions, applying the experience of town-planning solutions taken from the Italians and the Poles. The main subject of the paper – the urban planning of cities in the Courland and Semigallia Duchy during the 16th–17th century. Research problem – cities created in Renaissance traditions characterized by a regular layout, but buildings made by local masters gave artistic expression to the urban environment. Building facade solutions conformed the people’s taste in the decorative element and building material application. The architecture and spatial peculiarities of cities of the Duchy of Courland and Semigallia in the context of the Renaissance epoch building in Italy and Poland has been studied insufficiently. Research novelty – the Renaissance-era planning and architecture of Mitau, Bauska and Friedrichstadt as the major cities of the Duchy of Courland and Semigallia has been analysed in the regional and European context. The goal of the research – to determine the common and different features of the Renaissance period’s urban planning and building of cities, which now located in modern Italia, Poland and Latvia. Main methods applied – this study is based on research and analysis of archive documents, projects and cartographic materials of urban planning, as well as study of published literature and inspection of buildings in nature.