When visiting ancient sites like Machu Pichu, The Pyramids or Stone Henge we are asked to marvel at the amazing astronomical skills of the ancients. At the equinox or the solistice we are told the sun shines just so and this proves that the builders were really amazing blah blah blah.

Here is another theory. The two fixed objects in the sky are the North Star and the Southern Cross. if you build your big thing facing one of them on the solistice the sun will rise and set at exactly a right angle to the direction and amazing things will happen.

Look at this picture taken at the spring solistice:

Ignore the dog. My house was built facing north. When the sun shines in my East facing office window on the spring solistice it shines all the way into the front hall. Is this proof that the builders of my house were great astronomers or the unintended consequence of building the house facing north in the first place.