Damien Cave reports on the visionary plans of architects Delfín Montañana and Elías Cattan.
Their proposal would "restore at least three rivers, replacing busy roads with a ring of water and parks around the city center. A few lanes for cars would be allowed on the outer edges, but walking, bicycling and mass transit would take precedence. There would be fish and birds living in the river, and driving across to the urban core would mean paying a congestion tax.
"It's urban surgery," Mr. Cattan said. "It's not acupuncture."