If the subway to the sea is an expensive dream worth sticking with, the same can't be said of the city's fantasies of turning Grand Avenue into our Fifth Avenue or Champs-Élysées.

For more than 50 years we've used the section of Grand that runs atop Bunker Hill as a petri dish to test new theories of city-making. In the 1960s it saw widespread demolition in the name of urban renewal. Then it became a kind of murderers' row of buildings by famous architects, with only Walt Disney Concert Hall living up to expectations.

Now it features an attractive but hidden green space, 12-acre Grand Park. A museum holding Eli Broad's collection of modern and contemporary art, a $130-million building atop a publicly subsidized parking garage, will open next year. And when Metro's underground Regional Connector is finished by 2020, Bunker Hill, with a station at 2nd and Hope streets, will be tied fully into the mass-transit network.

What has all that investment added up to on Grand Avenue? A street that barely has more urban vitality than it did two decades ago.

The next mayor should drop the pretense that Grand Avenue deserves lavish subsidy and extra political attention. If the city does sink more money into Bunker Hill, it shouldn't be earmarked for more parking structures or trophy buildings. It should pay for direct improvements to public space — redesigning the sidewalks along the edges of Grand Park or adding public art along the avenue itself, perhaps in a program overseen by curators from Broad's museum or the Museum of Contemporary Art.

It would be easy to conclude that these problems will always seem intractable, or that the chance to solve them has come and gone. But the city charter gives the mayor more power than many realize. Through a combination of legislative savvy, smart appointments and canny use of the bully pulpit — along with an effort to give the planning department here the same broad, effective authority it enjoys in other cities — the next mayor could make headway on every one of these issues.

Cities around the world are now in direct competition with one another, for employers and employees, for tourists and investment dollars. In an age of globalization, it's easier than ever to see what improvements other cities are making to their parks, transit networks and infrastructure.

And easier than ever to measure all the ways Los Angeles is falling behind.

christopher.hawthorne@latimes.com