The Heidenmauer ('heathen wall') is a circular rampart or ringwork, two and a half kilometres long, which was built by the Celts around 500 BC. The wooden elements of the wall have disappeared over the course of time by rotting away, but the stones have survived. Copious numbers of pottery finds have enabled a very precise dating. Almost all the containers are hand-made, only a few show traces of having been turned; this technology first appeared after ch 500 BC. in the La Tène period. Other finds included iron, long knives as well as querns, pyramidal stones that were stuck point-down in the ground in order to provide the base for the milling of corn. In addition there is also evidence of milk production and iron smelting.
In the 4th century A. D. a small part of the circular rampart as well as the Kriemhildenstuhl below was used by the Romans as a quarry.
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.