Photo: The Klemm family – Paul Jr., Paul, Marybeth and Emily – who own and run Ohlin’s Bakery in Cushing Square.

There are three certainties in Belmont: the roads need repair, Ohlin’s Bakery at 456 Common St. will be open for the holidays (you name the celebration, the Cushing Square shop is ready for business) and, you will not find a better donut anywhere in Boston, or, as some have claimed, in the entire United States.

This year, the well-known Belmont institution – who hasn’t spent time enveloped in the wonderful warm aroma on an early morning visit? – marks its century of making and selling pastries, bread and, of course, donuts in the same general location since it first opened its doors in 1915.

“We have people come from far away who say, ‘We’ve come for your donuts,’,” said Marybeth Klemm, who runs the store with her husband, Paul.

In a world where upscale patisserie target hipsters with high-end donuts made with Pineapple Habanero, dark chocolate pomegranate and Sesame Sriracha priced at $3 a pop, Ohlin’s continues to outclass the competition with its traditional, homespun approach to the business.

The old fashioned, lovingly-worn storefront (it could be a movie set for a film set in the 1960s) is alive each day with the hustle and bustle as a wide array of goods – cookies, pies, cakes, pastries, bagels, scones, bread and cupcakes – are made on premises out back by Paul and his brother, and on weekends the Klemm’s son, Paul, Jr. lends a hand.

In the store, the staff rush in and out to fill and take customer orders, from workers picking up a dozen maple glazed donuts for their colleagues to families coming in for a birthday cake or to purchase creatively-decorated cookies.

CJ Jones, the manager of the Belmont Car Wash on Trapelo Road – another longtime Belmont family-run business – who returns like clock work daily to bring pastries to his operation.

“I come into Ohlin’s because they’re the best,” he said, coming away with two dozen assorted donuts, muffins, and cookies.

“I give them away to my customers for free because [the donuts are] so good. They come back to get their car washed because of the donuts!” he said.

The tightly-packed shop doesn’t have a place to sit and fire up your laptop for an hour of leisurely browsing. You serve your own coffee, get in line with the regulars and newcomers and pause to be called on.

And the wait is well worth it. The Boston Globe and Herald, The Harvard Crimson, CBS Boston, local publications and regional magazines such as Boston Magazine and the Improper Bostonian have all rave about of the family-run shop’s pastry selection.

Yet it’s Ohlin’s donuts that have won the highest praise as coming close to fried dough perfection. Whether ring or filled, the multitude of varieties – dipped, glazed, jellied – are the pinnacle of the art form, the DiVinci of donuts.

Having named the shop’s donuts “Boston’s Best” numerous years, the Globe this year pointed out Ohlin’s maple glaze as “one of the most aesthetically pleasing treats we encounter, overflowing with topping and beautifully drizzled with chocolate.”

Customers have made their views known writing in online review sites, such as Yelp and Trip Advisor. As one experienced reviewer noted: “This is a bakery that makes great donuts. And I’m going to repeat that: Great Donuts. The best I’ve ever had in Boston. Very likely the best I’ve ever had anywhere.”

There’s no magic to Ohlin’s success and longevity; just the dedication of a pair of families over the past century creating a landmark destination for confectionary sweat treats.

The shops history goes back to 1915 when the Ohlin family settled into Belmont and rented a spot in the then bustling Cushing Square which was in the midst of a housing explosion as estates were divided up into subdivisions.

Ohlin’s joined dozens of other small bakeries that populated nearly every square and main street in communities in and around New England before the day of large-scale bakeries and supermarkets.

In 1967, the Ohlin’s sold the store to Robert Klemm, the son of a dynasty within the Boston-area baking circles. The Klemm family started or bought dozens of small bakeries in Boston and its nearby suburbs including its first, Lyndell’s Bakery, which opened in Somerville in 1887 and still in operation.

Through perseverance, a solid produce line and a multigenerational cliental, the Klemm’s have staked their claim in a town where franchises – a third Dunkin’ Donut in Belmont is expected to open next year on Pleasant Street along with a Starbucks located across Trapelo Road – and other independent stores (Linda’s Donuts is just a few blocks down Belmont Street) compete for the loyalty of residents and those who work in Belmont.

Today, the tradition continues every predawn morning as Paul arrives between 1 a.m. and 2 a.m. to begin another day. By the early daylight hours, racks of donuts and other products are flying out of the ovens in a bakery where the heat is constant and relief is provided by a half-open door.

Marybeth became involved in the business “the day I said ‘I do’,” marrying into the bakery in 1984.

“Next thing I knew, I was getting up at 3 a.m,” she said, who started working at Ohlin’s as a 16-year old in an after-school job, meeting Paul who was working for his father.

It truly is a family business. Daughter Emily remembers her first “job” was folding boxes as a five-year-old in the corner of the store during the holidays, having graduated today to decorating birthday cakes and manning the store’s social media operation.

Despite its reputation for producing outstanding pastries, Ohlin’s is a small local business that depends not just on the big ticket items such as birthday cakes but also the single donut purchase to stay financially viable.

“We really rely on our local customers; we depend on them. But because we have a great reputation with our donuts, every day we get people who say it’s their first time here. Word of mouth is really important for our business to succeed,” said Marybeth.

“We are so thankful that they come to small businesses because we do work hard. My husband’s here seven days a week, getting up at midnight or 1 a.m. on weekends and 2 a.m. on weekdays. He doesn’t miss a day,” she said.

The Klemm children – which includes oldest daughter, Joanne Klemm Mann, who gave birth to their first grandchild, Christopher Joseph (CJ for short) on April 1 – also take time away from their own work; son Paul Jr. is an accountant and youngest daughter Emily is a recent graduate from UMass- Lowell working in public health with a view towards becoming a nurse.

“Right now, we do have them to help out,” said Marybeth.

If there is a dark cloud over the store, it’s what impacts many family-run business; who all continue the legacy. Paul said his children are leading their lives and will likely move on, leaving him and his brother running the bakery.

In fact, Paul has found it difficult to find someone who is willing to come aboard as a full-time baker, help that is sorely needed.

“It would be sad if we couldn’t find someone to continue what the Ohlin and Klemm families have created,” said Marybeth.

“But, hey, we just had a grandson. You never know,” she said, with a laugh.

Sometime in the early fall, the store will hold its 100th birthday – the actual day the business opened has been lost to history – “and I think we should have a ‘100’ cake to give out to everyone in town because so many are our customers,” said Marybeth.

Until then, customers can come by the store on the 4th of July, this Saturday, to pick from a selection of red, white and blue pastries for the evening’s barbecue or to help begin the Independent Day celebrations.

“Yes, we will be open and have lots of patriotic goodies!” said Marybeth.