Minneapolis' City Hall has a new "green roof" -- healthy, natural grass instead of the old, poisonous, stinky tar. It has several tangible benefits, but the biggest seems to be public education about sustainable development and green technology. Since you can't see it from the street, you'll have to wait for Google to update its satellite maps for the full educational effect.

Then again, you might have trouble finding it.

Have you looked at aerial views of Minneapolis on Google Maps? It's not as if we lack grass. Downtown aside, we look like the Amazon. You expect to see tiny lost-tribe people in Lowry Hill slathered with red paint and shaking spears up at the satellite.

The roof cost $460,000, which suggests that they went for the undercoat and the extended warranty. Might we find a cheaper way? Yes: We could slather some Chia Pet paste all over City Hall. That stuff grows anywhere, and if a gigantic building overgrown with a verdant sprout 'fro doesn't say Clean and Green, nothing does. Hire someone to stand by the doors with a machete and hack a path for people who want to come inside. Put it on Target Center, too. Make that roof like Carrot Top crossed with the Hulk.

Chia buildings might be cheaper, too. Consider the people who paid for the roof. Somewhere in town there's a couple who've had their house for 47 years and paid property taxes with the quiet, confident knowledge that they're building roads, funding schools, keeping parks clean. It's possible that they're considering the Green Roof bill, looking at their tax bill and realizing that a half-century of paying taxes doesn't begin to cover a quarter of the cost of patch of grass they will never see. They deserve our thanks.

They also deserve a bench. A nice little bench with their names on it. If they gave advance notice of a week or two, they could even visit it from time to time. They'd probably weed the roof for free.

jlileks@startribune.com • 612-673-7858 More daily at www.startribune.com/buzz.