"Urbanized"

In 1900, according to the London School of Economics, 10% of the world's population lived in cities. Five years ago the figure reached 50%. By 2050 it is likely to be 70%, or even 75.

That headlong rush into the world's cities — and its implications for the environment, architecture and the way we live — is the subject of "Urbanized," a sharp, good-looking documentary by Gary Hustwit that had its first Los Angeles showings Sunday evening at the Independent theater downtown. The film, which premiered this month at the Toronto International Film Festival, features interviews with the architects Rem Koolhaas, Yung Ho Chang, Alejandro Aravena and Ricardo Scofidio along with mayors, activists and planners. It is both a love letter to urban life and a cautionary tale about what happens when more newcomers crowd into a city, or the slums on its outskirts, than the place can begin to comfortably absorb.