Altentann Castle was originally surrounded by a sizeable moat; it consisted essentially of a high tower, attached stables, a chapel, four trade boxes and a gatehouse. It stood on an elliptical island about 16 m in diameter. A footbridge with two brick pillars led to the castle. The castle was surrounded by a circular wall from 1560. A Meierhof and another four ponds belonged to the castle; also a mill, stables for horses, sheep and pigs, a planting garden and several fields, an oven and a bird threshing floor are also mentioned.
The castle inhabited by the Uiberackers was severely damaged by fire in 1680; all wooden parts of the building were destroyed and only the vaults in the tower survived. The castle and outbuildings have been rebuilt. The castle was used as a granary. In 1701, the brick-built corridors were so dilapidated that they were supposed to be demolished, but this did not happen. Subsequently (1709, 1761), however, several people were given permission to take stones from the castle building. In 1762, however, repair work was carried out again. Between 1770 and 1778 hewn stones from Altentann Castle were used to build a bridge in Neumarkt. In 1796 only a few ruins remained on a hill surrounded by fishponds. The buildings that once belonged to the castle (Zehentstadel, Stall, Maierstadel) were used by the Hofmeierei in Salzburg.
At the end of the 19th century, only a small house surrounded by a nature park on the site of the castle is reported. This is said to have contained a statue of the Mother of God and a torso riding on a dolphin. This condition remained until the construction of the Altentann golf course in 1988. Today only the moat and the castle island can be seen, on the island there are still sparse remains of walls and a (recent?) well shaft.