If you were on the Capitoline facing north on a summer's day in 717 b.c.e., you would have witnessed, according to Plutarch, a large thundercloud drifting ever lower until it touched the swampy ground in the general area where the Pantheon now stands. That ominous mist was about to envelop and carry off Rome's sacred and mythical founder, Romulus. Livy described the fantastical scene occurring on the Nones of Quintilis (July 7), noting that,

On seeing Romulus's throne empty, the citizens unanimously recognized that their king had transformed into a deity; they quickly declared Romulus to be a god and the son of a god. This story is revealing in several respects: it suggests a popular recollection of the Campus Martius as a place to muster troops; it notes the early topography of the area as marshy; and, by describing Romulus's ascension, it creates the conditions for a sacred space. As discussed later in this chapter, many centuries after this mythical event, Romans were still making an annual pilgrimage to the Caprae Palus on a holiday called the Nonae Capratinae (Nones of the Goat), possibly to celebrate Romulus's apotheosis.