Simultaneously carried out archive and architectural research has led to astonishing new results, as neither the castle itself nor its builder or even possessor can be retraced before 1256. In the same year Perchtold von Achstein is referred to as liegeman of the mighty nobles of Kuenring.
Thus the wild romantic staging regarding the earliest information on ownership and construction of the castle stipulated in the 19^th century, is invalid.  In fact, the castle itself was only constructed around 1200 (1^st phase of construction), thus it is not surprising that neither the Freemen of Aggsbach-Werde nor the Freemen of Aggswald-Gansbach can be retraced to Aggstein in the 11^th and 12^th century. At that time the central forest district belonged to the famous dynasty Kuenringer, who most certainly can be considered as initiators of the construction of the castle.

Furthermore no evidence has been found regarding the fact that the Castle Aggstein was destroyed by Austrian Dukes due to riots caused by the Kuenringers in 1231 und 1296. Only earlier documents recorded from 1429 mention the invasive destruction due to a conducted crime done to the brickwork which can be verified around 1300, leading to the extensive reconstruction of the castle (2^nd phase of construction).

The reconstruction of the castle was forfeited, due to it being described as a “barren house” („ödes Haus“ ) and a “castle barn” („Burgstall“ ) in the records as well as in the construction table in 1429. The dilapidation process only coincides with the foundation of the proximate charterhouse “Aggsbach” in the late 1300´s, by the owner of the castle at that time, Heidenreich von Maissau, superior Schenk, the marshal in Austria and his wife Anna. As the Carthusians did not allow any castles to be built on their territories, they immediately appealed against the Aggsbach Castle, which most probably brought about the ruin of the castle.

On the 12^th of June 1429 Duke Herzog Albrecht V., the later Kaiser Albrecht II., bestowed upon his faithful valet Scheck vom Wald “das öd Haws genant Akstain, das etwenn von untat wegen zerbrochn worden ist und noch also oed ligt, …daz er und sein erben dasselb oed Haws und Purkstal….wider gepawen und gemachen mugen nach iren notdurften … (translation: this barren house and castle barn called Aggstein broken down by a crime and still remains destroyed, so that he and his heirs shall reconstruct it in the manner that is needed).
 

According to the construction table, the reconstruction done by Scheck commenced exactly three months later (3rd phase of construction). The beneficence of an eternal Mass in the castle chapel St. Georg and Kolomann marked the completion of the construction in 1436. In 1438 Scheck was given the privilege to raise a toll in perpetuity at the Danube (“Donau-Maut”).

Scheck was forcibly relieved of his goods, titles and the castle in 1463, as he apparently misused his rights and privileges. Soon, frightful stories entwined upon his rough and vicious character, stories such as the legend of his “garden of the roses” historically handed down in 1621. Even Scheck’s successor, Ulrich Baron of Graveneck disgruntled the Kaiser by raising insubordinate customs and tolls. From 1477 and onwards the Kaiser employed tenants and caretakers to manage the castle.

In 1529 the castle experienced its second forceful destruction when it was looted and ravaged by marauding Turkish troops. 2 years later these happenings prompted King Ferdinand of Austria to not only restore the castle but also to reinforce its fortification, at the remarkable cost of 4000 Gulden (appr. 220.000 €) - marking the 4^th phase of construction. In 1606 Kaiser Rudolph II sold the castle, including lordship and toll privilege to the widow Freewomen Anna von Polheim. She decided to invest her money in the buildings formerly held by her in pledge, in order to use them more efficiently in future.
(5^th phase of construction).
After the Thirty Years’ War whilst the Aggstein castle was guarded by an imperial troop, the owners of the castle altered rapidly. Towards 1765 under the reign of Sir von Starhemberg the administrative regime of Aggstein was relocated to Schönbühel, marking the beginning of the final architectural downfall.
 

In the early 19^th century Prince Ludwig von Starhemberg halted the gradual demolition of the castle. He did this by conducting initial developmental measures (6^th phase of construction) which were continued by his direct successor Count Franz von Beroldingen.

As from 1922 the Counts Seilern zu Aspang-Schönbühel restored the ruin provisionally, to then lavishly develop it into a tourist attraction in 2004-2006.
 

The ruins of a second but smaller castle exist just beneath the ruin of Aggstein, attaining first mention in the archives as “Nidern Ackstein” in 1447. Apparently it was constructed simultaneously around 1200. The purpose of the lower castle was to control shipping traffic on the Danube and the road traffic trailing along the river. Due to the extremely high position of Aggstein it was unable to control the shipping, let alone block it. Furthermore, two guard-houses already referred to in 1324 which presumably formed a part of the toll station. The economic environment was made up of several farms, taverns, a mill, fisheries, wood gardens and vineyards.