The castle was erected between 1200 and 1609 in five periods or phases of construction, and by no means, as often claimed, newly constructed by Jörg Scheck vom Wald by 1429.

Judging by the brickwork, made from block-shaped stones partially arranged like fish-bones and seaming lines, the castle today features almost the same dimensions and shape as it did from the first time it was constructed. These types of arrangements of the bricks appear at the plinth of almost all buildings.

The old wall fragments found at the dungeon area and at the corner of the outer gate, suggest that the castle complex displays a similar extension to the one built on the eastern side, around 1429. On site, findings suggest that even then at least two external gates existed. The outer gate found in place of today’s external gate, the inner gate in place of the heraldry gate, where an old brick fragment becomes evident. To the front of both gates short access ditches, so called neck ditches, cut through the compact mount.

A historic illustration from 1542 substantiates the fact that an expanded Outer Bailey (“Vorburg”) extends into the hillside situated to the front of the outer gate. Both belays of the “Bürgel” and “Stein” were initially overhauled in a similar way as later. From the castellological point of view, the 50 m long hall extending along the southern side of the courtyard, is the most important building of the castle. Situated on the “Bürgel” was an angular low Fortified House, whereas the “Stein” comprises a similarly dimensioned Large Hall (“Palas”), a slightly larger chapel and the longer Maidens’ Tower („Frauenturm”).

The extensive restorations done to the brickwork around 1300 show the alleged destruction of Aggstein Castle by Duke Albrecht I. (1295/96) with the following subsequent restoration. Extremely extensive restoration work was done to the southern wall and the attached hall building. The old wall plinth and the walls foundations were used as substruction, with the exception of the Maidens’ Tower (“Frauenturm”) where the completion of the western side was relegated. The Palas obtained an interior wall and an “abort jutty” (“Aborterker”) alongside the nose (“Felsnadel” of the later known „Rosengärtlein“).

	As an additional gate yard was inserted between the outer and inner gates, the eastern corner between “Bürgel” and the southern ring wall were blocked by a short traverse, the reinforcement and the fortification of the castle are considered to be the only two completely new architectural works.

The construction between 1429 and 1436 hardly becomes apparent in the masonry as it very much resembles the brickwork of the 2nd phase of construction. Distinctive features include the whitish sandstones in the corners and openings as well as the double relief arches. Even though the castle fundamentally remained the same, substantial extensions were made.

Massive walls, so called “shield walls” which were several metres thick were constructed on the eastern side of the castle, where cannons approaching from the hilly terrain proved to be an increasing danger. The access had to be protected at selected points, especially at the 1st and 3rd gate. The „Bürgel“ was also reinforced by a bow-shaped encircling wall on the eastern base of the rock and by an offside extension towards the western side. A small building – which has almost completely disappeared until today – was put on the southern wall, presumably ending in the area of the later “Gate of the Well”.

Even the adjacent great hall in the western part underwent considerable modifications. Wide arched window chambers with large windows were incorporated, a new inner wall was erected and a new vault cellar was created.
Considerable modifications were also made to the hall building adjacent to the western part of the hall. Vaulting underneath the great hall, broad, arched chambers with large windows were incorporated. The erection of a new inner wall and the creation of a new vault cellar, also form part of these modifications.
A kitchen with a pyramid-shaped stone chimney and a semi-detached house for the courtiers (“Dürnitz”) were built opposite the great hall. The front side of the “Stein” facing the courtyard was changed in a spectacular way to make the passage of way through the entrance more difficult. This was done by raising the doorway and by constructing a drawbridge and a machicolation.
The adjacent „Maidens’ Tower“ received two more storeys as well as internal partition walls set on flying arches. The chapel as well as the great hall were also heightened and endowed with new openings.
Finally the pinacle was converted into the „garden of the roses“ (“Rosengärtlein”) by erecting a wall on top of it.

Various restorations such as the filling of the trenches and the reconstruction of the kitchen and house for the courtiers (“Dürnitz”), done in 1819, 1901 und 1922, depict the fifth phase of construction.
Further renovations concurred in 1945 sqq. as well as in the early 1970ies. It was not until 2004 that comprehensive restorations and revitalisations were carried out by covering and restoring the great hall and integrating new lavatories. The vaulted cellars (“Gewölbekeller”) underneath the great hall were refurbished and the wooden staircase leading to the “Stein” and “Bürgel” was revamped. A look out point was built on top of the 3^rd tower. The chapel was revamped with great effort and the gatekeeper’s parlour, built in the 17^th century, was used a little souvenir shop