An interesting paper on this subject:
On The Orientation Of Ancient Temples And Other Anomalies, by Raphael G Kazmann, "Aeon", Vol. 2, #2.
The quotes below are from this paper.
The first half the paper concerns the orientation (East/West, so that on the equinoctial day, the Sun shone through a gate and illuminated an altar). What the author found was that many excavations showed that new temples were built on the site of the old temple, but the orientations of the new temples did not match with the orientation of the old foundation upon which it was built.
The problem of differing orientations has been of interest for more than a century. In 1894 Lockyer published a book in which the orientations of 20 temples was discussed. He too had no idea why temples built on the same site should be oriented differently.
But that is the subject for another thread, although the cause of this anomaly may be directly related or the same as that which caused the vitrification of many ancient forts.
The last half of the paper is devoted to vitrified forts.
Archaeology seems to have been a principle hobby of James Anderson, a Scottish landowner. In 1777 he published his observations of ancient fortifications in Scotland. These included what he termed what he termed were the most remarkable of Scottish fortifications, those forts whose walls were vitrified.
The author (of the Aeon article) visited one of the sites at Knock Ferrel and found that Anderson's 1777 description was quite accurate.
James Anderson wrote:These walls consist of stones piled rudely upon one another and firmly cemented together by a matter that has been vitrified by fire, that forms a kind of artificial rock....
There are about 60 sites in Scotland and more in Northern Europe. The awareness of this phenomenon has led to more examples world wide. The capital of the ancient Hittite empire, Boghazkoi (Hattusa) had a wall that was 5 meters thick, what is left has at some point been vitrified.
A German archaeological expedition has been studying the site for more than half a century.
The explanation that the conquerors burnt the wall in the frenzy of their victory simply does not hold. The victors could just as easily torn down the wall, and there is no historical record of any victorious ancient army burning down brick or stone walls. And if they did, how did they achieve such high temperatures needed for vitrification? Some archeologists have suggested that the vitrification was part of the construction process. But that too, is flawed. Vitrification does not strengthen a wall, if anything it makes it weaker.
The author continues in his summary:
The paucity of defensible hypothesis points to a glaring deficiency in our current understanding of geological and cosmic phenomena.
[...]
Let us postulate a planet sized body that, for some period of time that might be as much as 2000 years, approached Earth periodically. The gravitational, electrical, and magnetic forces associated with such fly-bys could speed up the movement of tectonic plates, cause earthquakes, and could well result in rotating plates.
[...]
As to the hill-forts and the vitrified walls of Hattusa: These fortifications were built on the topographically highest points. Assume that there was a great difference in electrical potential between Earth and the heavenly visitor. As it passed overhead we can imagine that a series of gigantic lightning storms occurred, touching the high points briefly, much like the sparks in a rim fire spark plug.
[...]
The rock walls would be fused where the rocks touched. The rock walls of cities (and possibly some of the houses in them) would be fused by the violence of the energy exchange.