In 395 Rome was divided:Western Roman Empire (Imperium Romanum Occidentale) and Eastern Roman Empire (Imperium Romanum Orientale, Romania) or Byzantium on whose western side of Capital City Constantinople a strong defence wall was built, creating three-part planning that affected building traditions in Orthodox lands, also in Russia where Christianity was adopted in 10th cent., but in second half of 11th cent.it was introduced in Latgalian lands. In German lands two-part planning was made to Wartburg fortifications (1067–1075) after reconstruction (1140–1172), separating front-castle from Ruler’s residence, but in Livonia architectonically spatial structure of fortified building complex created by Germans was supplemented with a castle settlement , which in three-part planning developed as a separate structural unit. Current researches: American geographer J.Leighly (1895–1986) on the basis of local features emphasized link of Fellina (Vīlande), Wolmar (Valmiera) and Koknese Fortresses built in Livonia with the city. Estonian historian of architecture E.Raadik (1925–1969) together with prof.Dr.at.Voldemar Vaga (1899–1999) worked out a research “Viljandi arhitektuuri ajalugu feodalismi perioodil (XIII–XIX sajandi keskpaigani)” (1960). Historian, archivist R.Malvess (1905–1982) compiled “Building History of Koknese Castle. 13th cent.- 20s of 17th cent. (2010), but Dr.hist. T.Berga conducted archaeological research of Valmiera Order Castle (1988–1996) (2002). Historical, archaeological, architectonic research materials of Livonian fortresses have been included into series “Latvian Medieval Castles” published by Latvia History Institute. Estonian archaeologists A.Kodar and Dr. E. Russow published a new research “On Development of Town of Viljandi in Light of Earliest Archaeological Find Complexes” (2013). Impact of Byzantium fortified urban building structure traditions on 13th cent. German administrative centre planning in Livonia has been studied insufficiently.