Wild was the tumult, loud the din As ponderous rocks went thundering in. Ere set of sun, so toiled each crew, Ten leagues and four the structure grew; The labours of the second day Gave twenty more of ready way, And on the fifth, when sank the sun, The whole stupendous work was done.

In plain words: The work is loud and wild as giant rocks crash into the sea. On the first day they build fourteen leagues, twenty more on the second, and by sunset on the fifth day the whole bridge is finished.