The Harbor of Trajan was built because of the unreliability and inefficiency of Claudius Port in a more inside area with an hexagonal shape excavating and lengthening the communication canal between the Port and the river (the current Fiumicino canal).
It has the double function of avoiding flooding and sanding up and to reduce the traffic of Tiber outlet.
To underline the great roman architectural abilities, the port had its banks with a “shoe” shape, an average profundity of 5 metres, it was sloping towards the sea and paved with big stones very useful for its maintenance.