Introducing commercial ventures into public spaces is a delicate balancing act. When done right, economic activity is a crucial ingredient in creating lively, well-used places. But when private interests overwhelm a place, they exclude regular users and diminish the place's identity. In this month's editorial, "Keeping the 'Public' in Public Space," we describe two commercial events that have overrun public spaces to the detriment of the people who use them: "NFL Kickoff 2003," which cut off portions of the National Mall for an event that launched both the new football season and a new soft drink from Pepsi; and "Mercedes Benz New York Fashion Week," an invitation-only event that keeps regular users off the lawn in Bryant Park for several weeks every year. The pictures say it all:

Preparations for "NFL Kickoff 2003" made large portions of the Mall inaccessible for days leading up the event.

Logos for Pepsi and other event sponsors covered fences around segments of the Mall during "NFL Kickoff 2003."

Regular users of Bryant Park are forced off the lawn as Fashion Week tents go up.

The free HBO movie series in Bryant Park is a good example of commercially-sponsored activity that works. Open to all, it attracts quite a crowd even on rainy days.

Cola Wars abroad: Invasive commercialization knows no boundaries, as these dueling kiosks in New Delhi, India amply demonstrate.

Is it still public transportation if it's covered with registered trademarks? Surely there must be better ways to generate revenue than turning trains into rolling advertisements.

At London's new Canary Wharf development, a car show provides a sorry excuse for real activity in this ostensibly "public" space. Apparently not content with simply dominating the street, now car manufacturers are crowding parks with their product as well.

Even Times Square can go too far: This giant Cadillac looks like it's about to run over pedestrians.