I have just witnessed the setting of the sun at solstice here in Tenerife, which is 'exactly' in line with the edge of a pyramid. Yes, believe it or not, a pyramid. There is no archeological evidence to suggest that the pyramid is more than 200 years old, but of course there are those, doubtless connected with tourism, who would claim a much earlier date.
Now I know that the date of solstice will change, but I can't work out whether with time the actual direction of the setting sun at solstice will change, and if so, by how much. Those who suggest that the aligment is coincidental would have to explain another curiosity that there is another aligment, namely three clearly marked points 'exactly' in the direction of the rising sun at winter solstice, in almost the opposite direction. Again, I can't work out whether there is a latitude at which these two directions are exactly 180 degrees apart. The situation is complicated by the fact that the sun sets at the summer solstice behind a mountain range with an elevation of around 15 degrees, because one hour later I saw the sun set again, in the sea, on the other side of the island.
My question is really whether this direction of setting sun changes sufficiently with time to be evidence for the age of the pyramid, assuming that there is a connection between it and the orientation of the pyramid.