There is one thing — the only one to be totally sure about: everything will eventually disappear. The city, the streets, the buildings, even we ourselves and our children. The time will pass and the piers of this grand bridge will go shaky, fall down, fold as domino row.
This basically means, if things are not eternal — and there are no eternal things — we can change them as we want. Everyone has something unshakable, unchangeable, but it is not true.