The Mujāni castle was built by the vassal of archbishop of Riga, the von Rozen family, at the end of the 15th century. During the Polish-Swedish wars of the seventeenth century it passed from hand to hand. Eventually, it was destroyed during the Great Northern War at the beginning of the 18th century.
The walls of the castle formed a quadrangle with a side of about 37,5 meters, on the north side of which there were two round towers. Their diameter was 13 meters and the thickness of the wall was 3 meters. The original height of the towers is unknown, preserved until today reaches about 9 meters. The main gate in the four-sided tower was located in the south-eastern part.
To this day, only the north-western tower, known as the White Tower, has survived. There are also relics of the wall nearby. The tower is covered with a wooden protection structure.