In 1264, castrum Hackenberg is mentioned as a site for document sealing. After the last Hackenberger died, the property passed to Alber Stuchs von Trautmannsdorf in 1382. Christoph Kuenritz bought and converted it into a Renaissance castle in 1543. Plundered in 1620 during the Thirty Years' War, it remained devastated until Sigmund Friedrich von Sinzendorf purchased it in 1650. His nephew, Theodor Reichsgraf von Sinzendorf, remodeled it into a Baroque palace between 1679 and 1677. After Prosper von Sinzendorf's death in 1822, it passed to the Reuß-Köstritz princes but fell into disrepair.
In 1945, it came under Soviet administration as German property, and in 1955, it was returned to Prince Reuß. Artists from the Vienna Group, including Friedensreich Hundertwasser, moved in from 1959. Captain Josef Steiger bought it in 1974, and in 1986, Horst Wächter, Hundertwasser's former assistant, acquired it. The Osmann family took over in 2020, with Horst Wächter remaining for historical research.
The four-story structure features Renaissance geometry and proportions, with medieval foundations. A cosmological mysticism, likely embedded during the 1679 Baroque renovation, is present. The four wings align precisely with the cardinal directions, enclosing a rectangular courtyard. The southern wings retain colorful ceiling frescoes and stucco decorations.
Access is via a short alley in the northeast, crossing a stone bridge into a frescoed entrance hall, leading through the courtyard with an octagonal fountain to a three-bay shell grotto, the 'sala terrena,' decorated with statues, frescoes, shells, and stucco, extending into the garden. The former access extended over the moat to a landscaped area with a Baroque-era artificial lake.
The Initiative Hagenberg association hosts cultural events at the castle.
The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.