There are plenty of places where streets are made pedestrian-only once per week, or even multiple days per week, for farmer's markets, flea markets, etc. and th

There are plenty of places where streets are made pedestrian-only once per week, or even multiple days per week, for farmer's markets, flea markets, etc. and they reliably bring a crowd. In a way, getting rid of cars is the special event: increased foot traffic, food vendors, outdoor seating, and other events like markets and live music tend to follow on naturally. Apart from pedestrian streets, you also see this in well-integrated urban parks and plazas like Union Square, Washington Square, or Bryant Park in NYC.