Poem Question

[rfmcdonald]

How many dawns, chill from his rippling rest
The seagull's wings shall dip and pivot him,
Shedding white rings of tumult, building high
Over the chain bay waters Liberty --

Then, with inviolate curve, forsake our eyes
As apparitional as sails that cross
Some page of figures to be filed away;
-- Till elevators drop us from our day . . .
- Bret Crane, "To Brooklyn Bridge"

Who can identify the subject of the first two stanzas of this Crane poem?