Cairo, Egypt, in its history[?] has had a significant number of fortified gates protecting both inner and outer city. Apart from the purpose of defense they were also used for differentiation of the varied social and economic classes. Often the gates were heavily decorated as artistic pieces.
... (In this case, the parabola does not intersect the x-axis at all.)
Note that when computing roots numerically, the usual form of the quadratic formula is not ideal. ...