Niagara from the 19th Century

Niagara Falls at Night

Niagara Falls at Night

Frederic Edwin Church - Niagara Falls from the American Side, 1867 National Gallery of Scotland, Edinburgh

A panoramic shot of the Falls (American on left and Canadian on Right) from 1896

American Falls with Canadian Falls 
in Background  Summer

American Falls Winter

For nice shots of the Falls try http://www.iaw.on.ca/~falls/