Flak towers (Flaktürme) were eight complexes of large, above-ground, anti-aircraft gun blockhouse towers constructed by Nazi Germany in the cities of Berlin, Hamburg, and Vienna from 1940 onwards. The towers were used by the Luftwaffe to defend against Allied air raids against these cities during World War II. They also served as air-raid shelters for tens of thousands of local civilians.
In Vienna military authorities chose the Augarten as one of several places to erect massive buildings for anti-aircraft defence to protect the inner city from Allied bombing. During summer 1944 the construction of a 55 metre high tower with platforms for anti-aircraft guns and nearby also a 51 metre high control tower was begun but not finished. Their remains are still visible in the middle of the park. Moreover during the war hundreds of cubic metres of rubbish were dumped on the site whilst armoured vehicles criss-crossed the garden and - as it is supposed - common graves were dug for hundreds of war victims.
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.