The Teutonic Order, a corporation dominated by the lower German nobility, welcomed non-noble people and non-Germans and had taken over the Dobrin Swordbrothers and its properties in 1235 and after the heavy defeat on 22 September 1236 in the Battle of Saule, took over the Livonian Swordbrothers and its first fortified secular power centres as Segwold (Latvian: Sigulda) and Wenden (Latvian: Cēsis) irregular fortified yards (Latin: castrum) at the significant trade road Riga–Pskov. On 12 May 1237, the Brotherhood of the German House of Saint Mary in Jerusalem in Livonia, an autonomous branch of the Teutonic Order for the subjugation of the Baltic tribes was formed by the support of the Pope (1227–1241) Gregorius IX. The Livonian State (1237–1561) was established. Statutes of the Teutonic Knights determined that convents had to live in monasteries. Fortifications of the Swordbrothers were rebuilt. The quadrangular military complex (Latin: castellum) consisted of a defensive wall and four blocks around the courtyard. Research goal: analysis of Segwold and Wenden castles built in two chronologically different construction periods and their impact on the settlement planning. Research problem: it is necessary to understand the specifics of the architecturally complicated construction of both fortified complexes. Research novelty: analysis of spatial development of Segwold and Wenden structures. Research methods: studies of archive documents, published researches, urban planning projects, cartographic materials and inspection of castles in nature.