The conventual castle in Ventspils (Windau) in the rank of commandry, was erected by the Teutonic Knights in the late eighties of the thirteenth century. Its first commander, Detlev, appeared in documents in 1291. Along with the castle, the nearby settlement developed, becoming the only medieval sea port of Courland and the Hanseatic city. In the fifteenth century, during the visitation of the central authorities of the order, it was noted that there were only seven knight brothers in the castle, five less than the rule provided, according to which there should be at least twelve of them.
In the 16th century, due to its western location, the castle was not occupied by the army of Ivan the Terrible. After secularization of the Livonian branch of the Teutonic Order, the city and the castle became a part of the Duchy of Courland and Semigallia, the vassal of the Polish-Lithuanian Commonwealth. The golden period began for the city, which became the main port of the duchy, the place of production of seagoing ships and an important commercial center. At that time at the castle tower it was usual to light a fire, serving as a lighthouse. Rich Ventspils became the subject of fights between Poland and Sweden, the most serious of which took place in the years 1658-1660. As a result, the castle was seriously damaged. Renovated at the end of the 17th century, from 1706 to 1835, it served the local residents for the church, and then there was a prison there. After Latvia regained its independence, renovation works began.
The oldest part of the castle was probably a massive four-sided tower, placed in the south-eastern corner of the later stronghold. At the latest by mid-fourteenth century, a four-wing castle complex was built with a square courtyard surrounded by buildings. They housed the order rooms on the first floor: the chapel in the east wing, the chapter house in the north wing, and the dormitory and the refectory in the west wing. It is not known if the castle had an infirmary. The chamber of the commander was quite unconventionally in the main tower (similarly as in the Wenden castle). The communication between the rooms on the first floor was provided by a wooden cloister. The other floors served as defensive and economic functions. There were stables, a kitchen and perhaps a treasury on the ground floor.
The castle in Ventspils, though destroyed and rebuilt many times, is one of the better preserved strongholds in the area of Courland. Although it lost its original stylistic features, its basic architectural shape resembles a medieval conventual castle. An additional advantages are preserved frescoes from the fifteenth century and numerous internal architectural details in the form of a portal from the fourteenth century, or gothic niches in the thickness of the walls. A museum has been operating in the castle since 2002, in which archaeological finds, exhibitions of the history of the castle, interactive presentations and the restored chamber of the Teutonic commander are presented.
Borowski T, Miasta, zamki i klasztory, Inflanty, Warszawa 2010.