A skyscraper as a huge diffraction grating

The Intesa Sanpaolo Tower in Torino behaves like a huge "diffraction grating". The facade is a doudle-skin one, the outer skin being mabde by a steel frame an orientable transparent panels. This outer skin  becomes a huge optical device.
The south side has only the central part covered by the doudle-skin. The rest is covered by photovoltaic panels. In the proper incident sunlight,  we can see the central part dispersing the white light in colored beams. Here two images of the phenomenon.

The sequence lasts 10 minutes. 

For more details, read please this article
A skyscraper as a huge diffraction grating

Vito Volterra

Vito Volterra and his commemoration for the centenary of Faraday's discovery of electromagnetic induction, https://hal.archives-ouvertes.fr/hal-01353959/

On the Karnak Temple and the Sun Hierophany

The Karnak Temple and the Motion of the Earth's Axis

Article published on SSRN Journal.

Abstract: The Karnak Temple complex comprises a vast mix of temples, chapels and other buildings. Its construction began during the reign of Senusret I in the Middle Kingdom and continued during the Ptolemaic period. The temple was the main place of worship the Amun-Ra, the Sun God. Not surprisingly his temple has its axis aligned along the sunrise azimuth on the winter solstice. Here we will discuss how the motion of the Earth’s axis has altered, in four thousand years, this alignment of half a degree.

http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2795239

Sun hierophany at the temple on the winter solstice

Whistling Sling Bullets Were Roman Troops' Secret 'Terror Weapon'

Whistling Sling Bullets Were Roman Troops' Secret 'Terror Weapon'

These bulltes have been discovered at the site of the  Earthwork of the Burnswark Roman Siege  Site