One of the commitments that Paris made for this summer's Olympics was ensure that every single competition venue was served and accessible by public transport. In fact, if you look on their website, it clearly says "no venues in the Paris region are accessible by motorized vehicles."

For those who attended, this seems to have worked out quite well. So much so that Los Angeles just made a similar commitment for the 2028 Olympic Games (excerpt from the New York Times):

L.A. mayor Karen Bass said Saturday the city is working on expanding its public transportation system to hold a “no-car Games” in four years, which means spectators will have to take public transportation to all Olympic venues. To accomplish this, she added that L.A. will need more than 3,000 buses and plans to borrow them from around the U.S.

Of course, the built environment of Los Angeles is slightly different than that of Paris'. One was built around the car, and the other was not. And I think the success of Paris 2024 shows how a robust public transport system is uniquely equipped to absorb significant demand shocks when needed.

Here's an excerpt from Le Monde talking about transit during the games:

Not only was the audacious gamble of organizing the first Olympic Games completely accessible by low-carbon public transport, on bicycle and on foot successful. Not only was transportation to the many competition venues scattered around Paris and its surrounding region fluid. But the transit network and its agents also proved their ability to ensure, thanks to planned initiatives and adapted resources, fast, reliable and even pleasant travel. What's more, the Paris Olympics offered the pleasing spectacle of a large city mostly freed, for a time, from the clutches and nuisances of automobile traffic.

But regardless of built form, both of these examples represent one of the positive externalities associated with hosting the games. They force cities toward massive positive change, and that's always a good thing.