Dun Troddan Broch in Glenelg, Scotland
Dun Troddan is one of two ancient Brochs in Glenelg of north west Scotland. It dates to the Iron Age, about 2,000 years ago (1st century BC or AD). The Glenelg Brochs are the two best surviving examples in mainland Scotland with much of the external walls remaining and some internal stuctures visible. The Broch belongs to the "Atlantic Roundhouse" class or building though there exact origin is nor clear with little study and contradictory expanations offered. One theory is that Brochs were a defensive structure similar to a castle. However the hollow design of the wall is one of lightweight not strength and the location of many Brochs seems to be of little strategic importance.
Brochs are round buildings with a single door on one side. They have high external walls and to some degree resemble a modern day power station cooling tower shape. The walls are of dry stone construction with no mortor. They vary in diamiter from 5 to 15 metres. The walls are typically 3 metres thick and of a hollow construction. So an outer wall and inner wall are built with a gap between. Large flat horizontal slabs of stone link the inner and outer walls forming galleries. It is possible to walk within the space along the gallaries between the inner and outer walls, though it is crampt. Most remenents of brochs only have a few metres of walls surviving. However, here at Glenelg, the Dun Telve and Dun Troddan Brochs stand to over 6.5 metres. One example at Glen Mousa in Shetland is best preserved and stands at 13 metres tall. However it is not clear wither this was typical of all Brochs.
Beside the door of the Brochs, in the wall, are remains for where a large wooden framed door would once have stood. There are holes in the wall for a stout bar to go accross the door. Beside the door there is usually a resess in the wall often called the guard cell. However there is no evidence to who what this small room was actually used for. I suspect that some archaeologysts let their imaginations run too freely.
Within the broch there is some evidence for wooden internal structures. Features in the walls suggest supports for floor beams to create a one or more stories within the building. Due to the top of most Brochs being distroyed by time, little is know about the roof structure but it seems likely that there would have been one. The exact shape is open to speculation.