The connection between astronomy and monumental architecture is an important element for the interpretation of hundreds of archaeological sites, as we shall soon see. But why? First, we must understand that in ancient times the sky was linked to the management of power. In fact, the connection between astronomy and power arises from the fact that human beings need a worldview, or cosmos: a framework of notions, social structures, religious beliefs in which they can accommodate their own existence so to feel safe and comfortable. A fundamental point of any worldview is to put order in space and time. Space and time are in fact, of course, natural concepts, but the flow of time and the structure of space need to be adapted to the human existence. Space typically becomes ordered in the human's mind once the four cardinal directions have been identified, and this operation is connected to astronomy, since ancients used the motion of the Sun and other stars to find the cardinal points. Time becomes ordered as well when the natural cycles have been framed and regulated through the use of a suitable calendar. Again, astronomy is fundamental to this aim, either for the establishment of a solar or lunar calendar, or for the timing of activities – ritual or agricultural – by using the stars. Further, any worldview needs, besides order and time framing, also a key to what is inexplicable and a hope for afterlife. Therefore religion is also connected to nature and the natural cycles, and in particular, to the sky. Typically, temporal power was the warrant of such a cosmic order, the keeper of the relationship between humans and nature. As a consequence, it was directly connected with the sky in unaccountably many cultures. For example, many Egyptians pharaohs considered themselves sons of the Sun God, or even identified with him. The Inca rulers claimed to descend directly by the Sun, and the appearance of a star – a comet actually - was used by Augustus to declare the divinity of his father Cesar and consequently, of himself. Establishing a cultural memory, assuring the stability of the worldview and therefore of power, requires the construction of monumental architecture. Monumental architecture was therefore introduced in most cultures as an explicit representation of power. And due to the connection between religion, power, and nature, it usually incorporated a series of symbolic references to the sky. It is here that astronomy comes into play, with a mechanism which was first clearly described by the historian of religion Mircea Eliade: the hierophany. A hierophany - meaning “the sacred reveals itself” - is an explicit manifestation of the sacred: of a god, of a message from a god, or also of a divine aspect of nature. Architecture is the means by which hierophanies are brought to the highest level of emotional participation, and astronomy is the tool for engineering such events. Consider, for example, a building aligned with the Sun that rises or sets in a particular direction. On the correct dates, the sunlight will penetrate in otherwise dark corridor, renewing an appointment with the divine, which was fixed by the architect at the moment of planning of the building. This is an example of spectacular events that occur regularly. These events can be divided into three main groups: hierophanies directly related to symbols of temporal power with a sacred value like, for instance the hierophany occurring in the Pantheon on the day of the mythical foundation of Rome; manifestations of the renewal of a god's powers in line with natural cycles, like the alignment to the winter solstice sunrise of Karnak's temple in Egypt; or the light-and-shadow effect which simulates a serpent at the equinoxes at Chichen Itzà; symbols of renewal relating to the afterlife, as the alignment of the Newgrange megalithic tomb, Ireland or the Akhet hierophany occurring at Giza, Egypt. All these examples will be discussed in details in the forthcoming lessons. In many cases, the stars in the sky and the astronomically oriented monuments on the ground have to be considered only as elements of a more complex scenario, which we can be called a sacred landscape. A sacred landscape can be the result of the addition of subsequent monuments during centuries, as occurred for the tombs of the pharaohs in the pyramid's fields of ancient Egypt or, a site can become sacred because it has special characteristics, like for instance geological or topographical features, as occurred for the most important pilgrimage centre of the Greek world, Delphi.
