WELCOME to Whittier, the Alaskan town where everyone lives, works and goes to school in the same building.

The 1950s former army barracks, Begich Towers, is almost all there is to see in this snowy, mountainous spot.

It is accessible only by a single-lane, four-kilometre tunnel, which closes each night at 10.30pm.

“We don’t have to leave this building if we don’t want to, so a lot of people don’t, you know, why would you?” says grade school teacher Erika Thompson.

The 14-storey block has its own post office, convenience store Kozy Korner, video store and city offices, where the community of around 200 people carry out their daily business.

It also holds a police station, a health clinic, a church, and a laundromat, with a B&B taking up the top two floors, according to a report in California Sunday magazine.

Begich Towers, known as BTI, was built along with Buckner Building as the most remote Cold War military base, its ice-free port used for bringing goods into Alaska.

But Buckner was abandoned just seven years after completion, when the military realised it didn’t have much use for such a far-flung outpost, Gizmodo reports. Now, almost nothing but BTI, and a bar, survives in the area.

Thousands of visitors flock to the unusual spot in summer, but in winter the city receives an average 6.4m of snow, and is buffeted by strong winds.

The extreme weather can mean people hardly go out. “It’s hard to stay healthy in a town like this,” says Ms Thompson, who runs fitness classes as well as teaching. “Our weather is extremely challenging, and we don’t have a fitness centre or gym except at the school. It just becomes normal to not move.”

Most people are employed by the City of Whittier, working on snow clearance, building maintenance and city administration.

“Everybody functions as part of a larger organism,” says photographer Jen Kinney.

Intertwined lives are played out in this one building, with police donating hydroponic equipment to the school vegetable garden after a cannabis bust on the 12th floor.

The teacher says her students are always on time. When your school is in the same building as your home, you don’t really separate the two. “It takes five minutes, depending on the elevator,” she says.

If townsfolk start feeling claustrophobic, they can drive under the Maynard Mountain to the nearest city of Anchorage, although residents avoid doing so on a week night.

“If you don’t make the 10.30pm tunnel then you’re sleeping in your car, which happens a lot,” says Ms Thompson. “The tunnel creates its own isolation.”

The Whittier Tunnel (or Anton Anderson Memorial Tunnel) was built for trains in 1943, but now traffic takes turns to drive down its one lane at a speed limit of 40km/h, according to Atlas Obscura. It remains the longest highway tunnel in North America.

An operator is on-call at all times in case the tunnel doors need to opened at night for an ambulance.

But life in Whittier is the opposite of lonely, Ms Thompson tells web channel Indie Alaska.

“I have friends and neighbours, students and co-workers who are right down the hall.

“It’s a condo association, and you get really cosy with your neighbours.

“It’s not that strange. Where I grew up everybody lived in an apartment building — but not the entire town.”