Paris is just Paris - everyone knows it has the Eiffel Tower, Notre-Dame Cathedral, Sacré-Cœur, well known landmarks and tourist attractions.
But what else makes Paris look like Paris?
It is also probably the architecture in the OTHER, lesser known and so-called normal buildings, or how designers have laid out the wide avenues.
Pretty geeky, but here is an interesting look at how a group of computer engineers have analysed thousands of geo-tagged images to understand more about what styles and trends feature in the French capital's architecture.
The team says:

"This is a tremendously difficult task as the visual features distinguishing architectural elements of different places can be very subtle. In addition, we face a hard search problem: given all possible patches in all images, which of them are both frequently occurring and geographically informative?
"To address these issues, we propose to use a discriminative clustering approach able to take into account the weak geographic supervision. We show that geographically representative image elements can be discovered automatically from Google Street View imagery in a discriminative manner. We demonstrate that these elements are visually interpretable and perceptually geo-informative.
"The discovered visual elements can also support a variety of computational geography tasks, such as mapping architectural correspondences and influences within and across cities, finding representative elements at different geo-spatial scales, and geographically-informed image retrieval."
Here is a video of how they did it:
NB:There is also a quiz.