Altdahn castle was probably built in the early 13th century. Certainly in 1236 the castle was being run by Frederick of Dahn as a vassal (Lehnsmann) of the Bishop of Speyer who, at that time, was Conrad IV of Dahn and may well have been a relative. The subsequent history of the castle is characterized by many wars and frequent destruction, that was, time and again, followed by rebuilding.
Altdahn was first destroyed in 1363 in the course of a feud between the Dahns and the Fleckensteins. In the end a squire took possession of the castle and carried out temporary repairs. In 1372 it was destroyed again and the squire driven out. In 1406 the castle was destroyed in the War of the Four Lords, which played out from 1405 to 1408 especially in the Bliesgau, 40 kilometres to the west. In 1426 and 1438 the castle caught fire without being caused by any military action.
After two centuries of relative prosperity Altdahn suffered further damage during the Thirty Years' War (1618–48). And right at the start of the War of the Palatine Succession the castle was finally destroyed in 1689 by French troops under General Mélac.
On 11 May 1820 a rockfall occurred, that caused the majority of the remaining ruins to collapse.
On the ridge of the Dahn castle group, which run roughly from east-northeast to west-southwest, Altdahn Castle occupies the two largest, easternmost rock outcrops, which have a total length of about one hundred metres. Its access is in the northeast, where the gateway and a small, water-filled neck ditch have survived. The lower ward is dominated on the north side by a horseshoe-shaped turret and, on the south side, by another tower of similar design.
Other notable remains of the upper ward on the western rock outcrop that have survived, include the north wall of the palas and a watchtower that, from the remains of an oriel, indicate that it may well have been used as a garderobe tower. The southern part of the palas was destroyed in the rockslide of 1820. This also opened the remains of a round cavern, in the rock in the shape of an inverted cone, that has been identified as a cistern or dungeon. On the remains of the eastern side, rusticated ashlar stonework is visible.
The isolated eastern castle rock is accessible over a narrow gangway. It used to support a small tower.
In 1877 the first conservation work was carried out by the Dahn Conservation Society (Dahner Verschönerungsverein) under the Bavarian government. In 1936, during the Nazi era, restoration work was restarted. After an interruption caused by the Second World War they continued from 1960 to the present day.
References:Trenčín Castle is relatively large renovated castle, towering on a steep limestone cliff directly above the city of Trenčín. It is a dominant feature not only of Trenčín, but also of the entire Považie region. The castle is a national monument.
History of the castle cliff dates back to the Roman Empire, what is proved by the inscription on the castle cliff proclaiming the victory of Roman legion against Germans in the year 179.
Today’s castle was probably built on the hill-fort. The first proven building on the hill was the Great Moravian rotunda from the 9th century and later there was a stone residential tower, which served to protect the Kingdom of Hungary and the western border. In the late 13th century the castle became a property of Palatine Matúš Csák, who became Mr. of Váh and Tatras.
Matúš Csák of Trenčín built a tower, still known as Matthew’s, which is a dominant determinant of the whole building.