Tiny spaces may be the 21st century's hip habitats, but there's actually nothing new about them. Burlington's eclectic inventory of buildings includes at least a few in the 500-square-foot range — some of them occupied, some not, and most of them built 90 or more years ago.

A local example that occupies a prominent location evokes a lot of WTF reactions, despite — or maybe because of — its Lilliputian dimensions. Every day, hundreds of motorists, cyclists and pedestrians pass the odd little structure on North Avenue situated diagonally across from the Burlington Police Department headquarters. Yet its front door is never open, and curious passersby can't peek inside, because its windows have been covered with plywood for as long as anyone remembers.

WTF is it? An opium den? The National Security Agency's Vermont office? A camp used by invisible urban hunters?

Nothing so romantic or weird.

It's a storage space for the tools of its owner, Andy Sheehan, who has lived next door in a red clapboard house for the past 23 years. A rare, and necessarily brief, tour of the tidy interior confirmed that the contents are entirely ordinary. There's a table saw; a couple of extension ladders laid across ceiling beams; a pegboard on which hang hammers, wrenches and other useful thingies; a power mower; a roll of insulation; and a lone tire.

"It's a woodshop, I guess you could call it," said Sheehan, who works nights in the University of Vermont's physical plant department.

Sheehan isn't sure how old the structure is, but he does know that the next-door house, which he also owns, was built around 1860. Bob Sabin, who has lived in a nearby house since 1972, said he's heard that the place functioned in the 1920s as a grocery store. It must have been an especially small mom-and-pop. Mighty cold, too, because the space is unheated, although Sabin thinks it might once have had a propane hookup.

The name "WANDA" is written in the concrete threshold of a door at the rear. Oh ho! So it's a secret love nest?

Not.

"WANDA" is a memorial inscription for Sheehan's beloved black cat — "the Queen of Ward 3," he called her. The feline died six years ago.

"I've thought of selling it," Sheehan said of the frumpy, grayish cabin that's structurally sturdy but badly in need of a paint job. "I've also thought of converting it into an apartment. There's been other plans, or dreams, too, but I'm OK with it the way it is."

Nearly 20 years ago, Mannie Lionni, a Burlington architect and activist, included a photo spread of tiny Burlington buildings in his irregularly published journal 05401. "They're intriguing to me because they're mysterious," Lionni said in an interview. "Who uses them? I wonder. What's their history?"

One of the places he highlighted in the spread was a house at 125 Howard Street, around the corner from what is now Tomgirl Juice Co. on St. Paul Street. Alan Longe, its owner, said the roughly 600-square-foot brown house with a bright red door and a small set of windows has been in his family since 1968. It was probably built in the 1920s, he figures, and may originally have served as a South End neighborhood barbershop.

A tenant has lived in the house for several years, Longe said. He thinks the man is a ham-radio hobbyist, owing to the sizable antenna array on the roof. The tenant would not comment.

Reg Lessor, owner of a tiny building at 179 Intervale Avenue in the Old North End, was more talkative. He currently uses the place as a garage, but in the 30 years since he bought it, "there's been all kinds of stuff stored in there," Lesser said. "It used to be filled with junk TVs from a repair shop on Archibald Street. Christmas trees were sold out of it at one point. And someone was building English racing cars there for a year or two."

In its next incarnation, the house is likely to be a storage space for the Chubby Muffin bakery and coffee shop across the way on Oak Street. The Muffin's manager is ready to rent the space, Lessor said.

A couple of blocks south at 129 Intervale Avenue stands a diminutive structure that's now attached to an adjoining home but looks like it might once have been a freestanding store.

Indeed it was, confirmed Eileen Lemieux, who lives in the house that members of her family bought 90 years ago. That's about 15 years after it and the adjoining space were built. Lemieux has traced the little building's use back to 1925, when Regis Petel opened a barbershop there. A second barber, Benjamin Robair, subsequently operated it until 1961, she said.

"Little places are popular now," Lionni said. "People should know, though, that there's a history behind that. You can see it here in Burlington."