Perchtoldsdorf Castle probably was laid out before 1000 AD, part of a chain of fortifications along the eastern rim of the Vienna Woods. One Lord Heinricus de Pertoldesdorf was mentioned in an 1138 deed, during the Babenberg rule. Their Perchtoldsdorf vassals continued to rule from the castle even when the Babenberg dynasty became extinct in 1246.
The conflict between the Habsburg emperor Frederick III and his younger brother Archduke Albert VI of Austria started an unstable period in the region. In 1446, many homes in the town were burned during the invasion of the Hungarian regent John Hunyadi. During this time, the castle was occupied by various rival forces, including mercenaries of King Matthias Corvinus from 1477 until about 1490, when Frederick's son King Maximilian I re-established Habsburg control over the area. This turbulent period interrupted the construction of the tower house (Wehrturm), the town's landmark with a height of 60 metres. The tower and other fortifications permitted a successful defense of the city against the Ottoman troops during the 1529 Siege of Vienna, while the surrounding area was devastated.
References:The Broch of Clickimin is a large and well preserved, though somewhat restored broch near Lerwick. Originally built on an island in Clickimin Loch (now increased in size by silting and drainage), it was approached by a stone causeway. The water-level in the loch was reduced in 1874, leaving the broch high and dry. The broch is situated within a walled enclosure and, unusually for brochs, features a large 'blockhouse' between the opening in the enclosure and the broch itself. Another unusual feature is a stone slab featuring sculptured footprints, located in the causeway which approached the site. Situated across the loch is the Clickimin Leisure Centre.