Conrad von Mandern started to built Order's Castle between Lielupe and Driksa Rivers in 1265. Building was finished around 1328-1340. Castle was convent type building with towers on corners and ringwall. At the time of Duke Gothard Ketler the castle was enwided and the new church was added. Old land fortification system was completed with connected moats and bulwarks in 1648. Old Mediaeval castle could not meet the needs of new Duke Ernst Johan Bieron so it was blasted commanding the building of new palace in 1737. By the time of construction operations between Lielupe River and new palace in 1997 the preserved parts of Mediaeval structures were discovered including details of 17th century entrance portal that now can be viewed in yard of new palace. Some parts of old castle and cannons were included in cellar walls of new building. Baroque style Palace was erected after the project by architect F. B. Rastrelli in period 1738-1771 (with break from 1740 till 1763). In its origins there were two wings connected to the main part creating U shape. Interior finish had rich Rococo style decoration. There were made separate premises for Duke’s charnel-house in socle floor in 1740. Since 1820 for these needs was used South-eastern part of socle floor. Palace was damaged by great fire of 1788. After forced incorporation of Dukedom in Russian Empire, the Jelgava Palace became the residence of Governor von Palen and housed the institutions of Courland Governory. Fortification system was partly damaged and later destroyed at the beginning of the 19th century, palace housed Napoleon’s Army hospital in 1812. Leaving Jelgava Town after the World War I the German Army burned palace down. Chamber of Agriculture started renovation in 1920. The fourth wing closing palace yard was built at the place of former stables after the project by architect E.Laube in 1937. Palace burned out at the time of World War II and reconstruction was finished only in 1961. Original interior finish has preserved only in ground floor premises.
The park is situated between Lielupe and Driksa Rivers. Parts of former fortification system (ramparts and bulwarks) were included as part of park relief.