The Nicollet Mall has been a shopping-district destination since the 19^th century, and has served for decades as the cultural and commercial heart of the city, but the partially pedestrian mall – first built in the 1960s – was due for another update. It will now run for 12 blocks through the heart of downtown, with new features built beyond the sidewalks and intersections.

There's a lot of outdoor appeal in a city known for being bike-friendly and walkable, and the urban design for new Nicollet Mall adds to the experience. New bars and restaurants, some with patio dining for the warm-weather months, will add to the nightlife and to the energy on the street. There will be 240 trees planted on the mall, along with landscaping updates. Yet what residents are excited about – including the usually more "hardhat" director of public-works engineering – is the public arts space.

Fans of the old Mary Tyler Moore Show might recognize the life-size statue of character Mary Richards tossing her tam into the air in the city she helped to put on the map, but that's not all there is to see.

What he's referring to is a kinetic sculpture that relies on anodized aluminium "leaves" to create art that's gracefully in motion, reminiscent of the region's prairie grasses blowing in the breeze or the rustle of the wind in the trees.

Essentially, Prairie Tree is a square stainless steel canopy, six meters on each side, perched atop stainless steel supports. The upper surface of the artwork, covered in thousands of aluminium vanes, will reflect the light and sky in a manner similar to the surface of a lake, Kahn says.

The Prairie Tree will be installed in a pocket park-like setting, next to trees and above the bench seats on a small plaza along the Nicollet Mall. Its shiny reflective motion, visible from a distance, also will serve as a meeting-place landmark and wayfinder along a stretch between Grant Street and Washington Avenue.

Other installations on the mall include the Light Walk, which will run for two blocks to the north of the Prairie Tree. The programmable LED display will feature colorful lights above pedestrians and embedded in the sidewalks beneath them.

An oversized sculpture by Tristan Al-Haddad called "Nimbus" will hover over a small outdoor theater space, in a cantilevered ring that appears to float while casting its light. In a different stretch, cutout metal lanterns created by Blessing Hancock will literally float above the streets.

Minneapolis officials are eager to show off Prairie Tree and the other new pieces when the Nicollet Mall reopens in fall, but they've promised that beloved art from the old mall will be there too. They include 77 manhole covers created as ornate medallions by Kate Burke, and cherished by Minneapolis residents.