Overall, Paris probably has the best parks of any city in the world. There are a great number of different types and sizes of parks, located in neighborhoods throughout the city. But their success is not simply a matter of variety or quantity, and not all parks are well-used. The real question is: "Why are some parks in Paris so popular, while others are not?"

To formulate an answer to this question, we decided to record the uses and activities in several different types of parks, both old and new, during the course of a week with good weather. We found that while some parks, such as Luxembourg Gardens and the Jardin des Tuileries, are very heavily used by a wide variety of people for a range of activities, parks like André Citröen and La Villette have homogeneous sets of users who do not engage in many types of activities.

Of course, centrally-located parks outdraw more remote places, but that is only part of the story. In fact, the well-used parks are often less accessible to pedestrians, with fewer points of entry or more highly trafficked exterior roads than the less popular parks. And parks such as Luxembourg Gardens and Place des Vosges thrive though they are not adjacent to any major tourist attractions. Clearly, then, it is not just geographical circumstance that makes some parks more popular than others; people make a greater effort to visit certain places. Why?

If you look at many of Paris's parks in plan, both good and bad tend to consist of an underlying grid that is used to lay out various paths (exceptions include Parc Montsouris and Parc Buttes Chaumont, which have more naturalistic contours), so the difference in use is not solely a matter of layout or design either. In the busy parks, sections of the grid are filled in with programmatic attractions or uses: This is one of the keys to success. As mentioned earlier, Luxembourg Gardens is packed with such activities. But in Parc Citröen, the grid is instead filled with physical elements--"rooms" defined very specifically by walls, hedges, or grade separations--in which activity is supposed to occur but with no specific program to draw people there. In fact, the rigidity of these rooms limits the way people can use them, discouraging any sustained activity.

This brings us to another crucial difference between parks: the quality of amenities. The well-used parks feature amenities that encourage interaction--movable chairs, playful sculptures, and touchable water features. The Jardin des Tuileries, for instance, has all these elements in abundance, with small cafés to boot. By contrast, Parc de la Villette is saddled with rigid, awkward public seating, and its sculpture is more intimidating than inviting. After the user's initial encounter with such poor amenities, he or she will seldom return.

The failure of parks like Citröen and La Villette is part of a very alarming trend that is taking hold in cities trying to achieve excellence in architecture and public space. Many of the city's new public spaces seem to be narrowly focused on "design as art," and these designs do not create places that measure up to the standards of the past. In fact, much of public space design today has become object-oriented and out of touch with creating comfortable places that allow people to express themselves fully. One reason may be that most new public spaces seem to have the singular goal of highlighting the identity of the designer rather than human use and comfort.