The statue in front of the building is of William Wilberforce; it was moved to Queen’s Gardens in 1935.
Excursion Steamer landing Passengers, Qunicy, Ill.
For larger version, click on image.
Google Street View (approximate). There’s not many riverside locations along here on Street View but, as best I can tell, that’s looking towards the site of Bangor’s Union Station (demolished), the tower in the postcard, from Brewer.