The Eiffel Tower stands on an oxbow beside the River Seine in Paris, France. The reason for its placement was due to it being the centerpiece of the 1889 World's Fair, which took place in the same region.
The placement of the tower and the World's Fair was not an accident. It is placed at a spot in Paris that is generally considered a cultural divide. Following the Seine upstream will take a visitor to the port and the slightly more bohemian and blue-collar part of the city. Going downstream leads into the wealthy and aristocratic parts of Paris.
Besides the Eiffel Tower, the banks of the River Seine are home to many architectural attractions. Most notably, Notre Dame and the Louvre sit beside the Seine, overlooking the river.