The Barbican tower with its thick walls is 21 metres high. Three lower storeys are squared, two upper storeys are octagonal. The measures of the base are … metres, thickness of the walls extends to … metres. From the ground floor there is access to the 1st and 2nd floors by the flight of steps, built into the wall, going further one must use wooden staircases.
The onetime Borkholm castell with squared groundplan possessed four rotund corner towers and a rectangular barbican in the middle of South-Eastern wall. The access to the stronghold was possible only through the gate tower. Due to difficult times there were usually guards, whose rooms were situated in the upper floors. In cold weathers the tower was heated with fireplaces on the 1st and 2nd floors, which are still there. Presumably those days the tower was equipped with bare necessities.
Porkuni castle was destroyed in the Livonian War and only the barbican tower is extant. The barbican was restored by the local landlord in the 1st half of the 19th century. The crenelated wall is not original, but comes from the 19th century.