A new architectural landmark has risen on a previously empty spot along Hiawatha Avenue, but what's inside may shock you.

Literally. It's a new Xcel Energy substation.

The new structure along the Midtown Greenway is one of just a handful of substations in the country with an aesthetic exterior. Architects used gold aluminum mesh to create a fabric-like wrap on the outside of the facility -- which will eventually be lit up at night.

During a recent tour of the site, architect Nina Ebbighausen with Architectural Alliance noted that more than 40,000 cars, light rail passengers and bicyclists will pass it daily.

“We’re standing on a site that is going to be viewed many times, not just by the locals," Ebbighausen said. "But also by people who maybe have never been to Minneapolis before and are arriving for the first time by LRT.”

The facility is one of two new substations that Xcel is installing in South Minneapolis. The other, on the Greenway between Oakland and Portland Aves., will also have an artistic wrap. Construction on that facility will begin in June (see rendering below).

The state's public utilities commission required the company to consult with community members about the aesthetic look of the structure. That advisory group that shaped the substation's design got a tour on Tuesday morning.

“This is the first where we’ve tried something like this that has more of an architectural feel," said Joe Samuel, Xcel's senior project manager.

The two future substations connected by underground lines along 28th Street, comprise Xcel's first new transmission corridor in the city in 20 years, according to a 2008 story about the project.

Those connecting lines were controversial. The city ane neighborhood representatives fiercely opposed an alternative plan to route the lines overhead or underground on the Midtown Greenway.

Samuel said that the project came in response to increased demand in the area. He noted development along the Midtown Greenway, as well as conversion of the Sears building into the Midtown Exchange.

"We have a lot of redevelopment that’s occurring," Samuel said. "And then with that higher density type uses, which have more electrical demand.”

Tuesday's tour was split into two visions of the site: architectural and electrical.

Ken Sheehan, one of the other architects, said that their firm had a hard time finding precedents nationally for an aesthetically wrapped substation.

“Our firm occasionally will pursue projects like this because we just think they’re really interesting from a design perspective and they have such a huge impact on the community," Sheehan said.

Notably, the bands of aluminum do not cover the entire structure. Ebbighausen said it wasn't practical to reach the top reaches of the facility, for example. But opacity and a lower buffer allow views of the sloping wires and cone-shaped objects connected to the transformers and circuit breakers.

"We thought one could actually celebrate some of the interesting features of the substation structure," Ebbighausen said. "So the mesh, the fact that it’s translucent, rather than opaque, was an important aspect to us."

The translucency was also important so that sun should shine on the Greenway, allowing snow to melt earlier in the season.

Inside, the complicated mass of metal are stepping down voltage from 115kV to 13.8kV. The current arrives from Xcel's Riverside, Black Dog and Sherco generating stations. It's then distributed at the lower voltage to neighborhoods.

The facility will be unmanned, which is why workers were putting the finishing touches on an 8-foot security wall Tuesday. Known as a Gabion wall, it is made up of rocks that are filled into metallic structures.

Atop the wall is a squirrel guard, which hinders the creatures from getting inside. When they do -- a fairly common occurrence -- they are easily electrocuted by touching two of the "phases" or being grounded while touching one.

These incidents, explained Xcel's Nathan Steward, are known as a "squirrel flashovers.” Birds have fewer problems, since merely sitting on exposed areas won't garner an electric shock -- the circuit must be completed. "Typically birds will sit on a [single] phase," Steward said.

Distribution from the Hiawatha substation will begin in the next month.