Coastal territories of Baltic Sea were subjugated applying military power – monk-knights’ orders. In conquered Prussian, Livs and Latgalian lands administrative centres were founded, where due to impact of residential building traditions fortified houses were built and building complex created on places appropriate for economic activity, creating formation of medieval urban structures. A strategic building for land conquest was a tower house which originally had quadrangle planning. Residential tower was included in fortified building complex, and construction volume obtained vertical emphasis for defence function. In Livonia by traffic routes market places and a fortress with a tower house formed settlements creating origins for medieval urban planning. In Prussian administrative centres four-building fortresses with a tower were built, but in architectonically spatial environment of trading cities Town Hall with a tower construction dominated. Previous researches: Estonian art hist. prof. Dr. ph. Armin Tuulse (1907–1977)published the first profound research on Livonian fortresses “Die Burgen in Estland und Lettland”(1942),but since 1999 historical, archaeological, architectonical research materials of German fortresses have been collated in series “Latvian Medieval Castles” published by History Institute of Latvia and in archaeologist prof. Dr.hab.hist.Andris Caune and Dr.Ieva Ose’s “German Castle Lexicon of Latvia from late 12th-17th cent.” (2004). Architect prof. Friedrich Lahrs’ (1880–1964) research on Konigsberg Fortress with dungeon is dedicated to Prussian fortress architecture. One of the most recent researches is prof.Dr.hab. Tomasz Torbus’ “The Architecture of Castles in the Prussian State of Teutonic Order” (2016). Evolutionary analysis of Prussian and Livonian fortified housing planning and structural construction during 13th-16th cent. has not been carried out in regional and European context and impact of medieval urban planning has not been assessed.