It’s a challenge to update a tired office building’s public spaces. Three new examples in downtown Minneapolis show what’s new, what’s possible and how modern design is still working its way through a phase you might call “playful incoherence.”

Consider first the atrium at 121 S. 8th St., the old TCF Bank building. When it opened in the early 1970s, it had a cafe, an aquarium, splashing water, warmth in the winter, light from the big skylight. It was something you’d show an out-of-town guest on the way to more interesting downtown spots.

By the time it closed two years ago, the atrium was an empty, dead space, a graveyard for every ’70s mistake. Ugly brick. Dated circular patterns on the floor. Flabby arches above, a joyless fountain below, a verdigris copper piece of art that looked like a virus in various stages of mutation.

How to make it look better?

Option 1: Fill it with concrete and just walk away.

Option 2: Fill it with water and add synchronized swimmers.

Option 3: Paint it white and fill the space with a massive staircase that would make Busby Berkeley think “Now that’s a bit much.”

Ryan, the company that revived the old building, chose Option 3.

In the old atrium, they installed a staircase that’s very wide. So wide that it has seating in the middle of it. Tiers of wood benches for lunchtime sitting, or impromptu collaborations. You know how you’re walking down the steps, and you get a great idea, but it’s forgotten by the time you get to the bottom? Now you can sit down mid-staircase and get some collaborating done.

The brown brick was painted white, something that was popular in the Mary Tyler Moore era. But the ground floor wasn’t painted, which makes it look as if the atrium was flooded with sewage that they haven’t been able to hose off. Instead of strange art on the wall there’s nothing permanent, which is probably a good idea.

Arty images are projected on the wall occasionally, but if you show up when there’s nothing in the projector, then the entire wall is the equivalent of the words “This Page Intentionally Left Blank” in a boring book.

There’s some colorful graffiti-style “urban” art under the staircase, which connects in a way to the raw concrete and chic — for 1974 — exposed ductwork in the adjacent entryway, but it doesn’t mesh with the style of the atrium.

Whatever that is.

In time, the space may be improved to the point where it’s No. 3 on a “Hidden Gems of Downtown” list, but for now it looks like a place you could rent for an event if the budget was tight.

Skyway with a view

The TCF skyway connects to the Baker Center block, four buildings grouped into one conceptual arrangement on Marquette Avenue between 7th and 8th streets.

From the outside, they’re separate structures with distinct appearances, but the skyway level has been redone to tie them together with clean, spare, antiseptic white spaces. It’s not particularly adventurous, which is why it’ll wear well and won’t look dated and silly in six years.

One of the buildings deserves a closer look. The former Investors Building is a textbook example of mid-century blandness: brick and stone, not a trace of ornament.

It wasn’t always so. When it was built in 1927, the Investors Building had the usual classical gewgaws stuck on its facade. In the post-World War II era, the gewgaws looked old and tired, so the building was brutally stripped. It has stood like a square old elephant ever since. How to make it look new?

In a perfect world, you’d re-skin the building at ruinous expense. In this world, the designers chose to refurbish the ground floor and open up the corner, the equivalent of new shoes and a sporty tie for an old beige suit.

It’s better inside than out. From the street, it looks like a compromise at odds with the rest of the building, but at least it says “something’s going on here.” From the inside, the windowed corners provide broad new views of Marquette and 8th Street. You can take a chair and watch the world go by, and the spaces feel rather intimate, a front-row seat on the great plotless story below.

The design of the spaces, however, has that eclectic modern confusion that pairs abstraction (the ceilings, with backlit beams crashing at odd angles, resemble the comic-book lair of Dr. Strange) with retro-chic materials like mirrored globes arranged beneath a new prefab ceiling that copies the old pressed-tin ceilings of the turn of the century, decades before the building was constructed.

It doesn’t quite cohere, but it’s pleasant enough to pass through.

A virtual sunset

At Marquette and 5th Street stands the Fifth Street Towers, the city’s tallest testament to the popularity of deep red stone in the Reagan era. What was rich and classy in the 1980s looks out of fashion today, but the buildings’ hue is overshadowed by their curvy corners and long strips of windows, recalling inventive industrial buildings of the 1930s.

Alas, the skyway level was vacant, dim and somnambulant. Solution: crowbar off the russet stone. Brighten the ceiling. Panel the walls with rich wood slashed with veins of white light. Add a giant video display cut into triangles, in case you like your sunset views served up in pie-shape slices

This is the most successful of the three makeovers. But then, the Fifth Street Towers had the most to work with — a broad, open plain connecting the two towers, and uninterrupted window views of the street below.

But when you take the escalator down to the ground floor, it’s like descending into the netherworld. All the life is upstairs, and everything down here is still dark. The skyway level has nothing to do with the rest of the building. Its relentless angularity is the opposite of the curved ethos of the building itself.

At least it’s better and brighter.

You could say the same about all three spaces. They’re modern, but these days modern seems to mean “here’s some old and new stuff in chaotic combinations until we figure out a dominant style again.”

Look at the IDS Center: early ’70s, but timeless.

The 333 South 7th Street, with its greyscale classical interiors: late ’80s, but timeless.

The monumental, impersonal corporatism of the City Center’s main tower lobby: late ’70s, but timeless.

Our culture doesn’t seem sure what we want these spaces to be nowadays, except that they should connote some new workplace model where offices have foosball tables and conversation pits, and one day a month where you can bring your dog.

We don’t know quite what we want, and it shows.