A triangular structure looms over Harvard Square, its large windows beaming light onto the street. Ribbons wrap around its granite columns and murals decorate the walls inside.

The building houses Curious George and Friends, a store remembered fondly by Cantabridgians as a friendly neighborhood bookstore. It closed four years ago and stood vacant, its windows dark and dusty, for another year.

Curious George and Friends then reopened under different ownership, but the store had a radically different mission. It no longer aimed to serve the liberal enclave of Cambridge alone, but to become a worldwide center for Curious George paraphernalia.

Renamed the World’s Only Curious George Store, it would draw tourists to the Square in its own right.

The store, like many a Harvard Square institution, has a storied history. It was conceived by the couple who wrote the Curious George series as they fled the Holocaust, dreaming of a quizzical primate, and settled here, just steps from the ivy-covered walls of Harvard College.

Under the watchful eye of the Harvard Square Business Association, Harvard Square has managed to preserve the historic charm that makes stores like Curious George unique.

Ruddy brick buildings stand along the streets that hug the university. Whimsical stores hawking honey or stationary are nestled between apartments and burrito shops. Unshaven musicians strum guitars to the lilting tune of Simon and Garfunkel songs. Burger joints reign supreme.

But despite the idyllic atmosphere, Harvard Square has fundamentally changed over the past several decades.

The historic heart of Harvard Square, once exclusively lined by small family businesses, now features mostly national chains. The three block radius around the Harvard T Station now hosts three Starbucks, a Panera, Chipotle, Qdoba, Pinkberry, and Shake Shack.

Some stalwart local businesses remain, but others have toppled to the looming pressure of high rents and online shopping.

“You have to be really savvy to survive as a brick and mortar business. People just click and shop now, you really have to fight hard for their business,” says Paul MacDonald, who owns the tobacco store Leavitt & Peirce. “Only the strong survive. You have to be really good.”

Many of the stores that have stuck around for decades now say they remain afloat because they carved out a niche as a tourist center, some filing hordes of visitors through their doors every day.

NATIONAL CHAINS ARRIVE

Bill Bartley has owned and operated Mr. Bartley’s Burger Cottage for over 50 years. He grew up around Harvard Square and says that he has watched the family businesses of his youth dwindle. He can now count the ones that remain on one hand.

When Curious George initially closed, for example, it was one of the last remaining independent bookstores housed in Harvard Square.

The Globe Corner Bookstore, which opened during 1982, had previously announced that it would shutter its location. The Harvard Coop was transferred to Barnes and Noble management, which continues to operate the store today. WordsWorth Books closed during 2004.

The Harvard Bookstore, whose windows look onto Harvard Yard from Massachusetts Avenue, is one of the few left.

As bookstores closed, national chains rushed to fill the void. Many of those stores now stand on what John P. DiGiovanni, president of the Harvard Square Business Association, calls “marquee corners.”

The first wave of national chains consisted primarily of clothing retailers. Abercrombie and Fitch, Pacific Sunwear, and Adidas all had Harvard locations. MacDonald remembers walking through the Square and spotting scantily clad teenagers from Pacific Sunwear advertisements plastered along shopfronts.

“It was just horrible,” he says. “It was the symbol that all that was good in Harvard Square was going down the tubes.”

Those companies eventually failed to generate the profits needed to stay afloat. When they folded, restaurants and eateries replaced them.

Starbucks has opened several locations around Harvard since 1996. The chain now operates ten branches around Cambridge. Yogurtland joined a Pinkberry last fall. Shake Shack was another highly anticipated arrival from New York. It opened earlier this year.

MacDonald believes that those openings speak to a broader trend across the Square.

“Harvard Square is losing its cachet as a shopping area and becoming a destination for eating and drinking,” MacDonald says.

Bartley notes that national companies are the only ones that can afford the high rents that abound on Massachusetts Avenue and near the T stop.

“A national corporation can afford to break even just to get the exposure,” MacDonald adds.

STALWARTS REMAIN

The tobacco store Leavitt & Peirce has stood on Massachusetts Avenue for more than 127 years.

Rowing oars and old Harvard photographs hang from its dark green walls. A carved American Indian perches above its dark windows—a reminder of the days when the young men of Harvard College would buy snuff boxes and cigars to puff under the vaulted ceilings of their dining halls.

Through world wars and protests, the store has flourished across from the Yard, but as demand for some traditional tobacco products fell, it has adapted its merchandise to include colorful pipes, board games, and jewelry.

Other stores have stuck around for decades as well.

Bartley’s Burgers has served its trademark chargrilled burgers for over 50 years. The dishes are named for local celebrities and politicians (you can guess that the family favors conservative candidates).

Hong Kong restaurant, where inebriated Harvard students flock for greasy dumplings and scorchingly potent scorpion bowls, hit its 60th anniversary this year.

Those stores sometimes owe their longevity to the landlords that rent property. Harvard owns a substantial portion of the Square and rents space to older businesses that include Leavitt & Peirce and Bartley’s Burgers.

Lisa Hogarty, then vice president for campus services at Harvard, told The Harvard Crimson three years ago that the university tries to offer leases to local businesses.

“Our focus is always on small businesses with unique offerings,” she told the Crimson. “We really don’t talk to national retailers ever.”

DiGiovanni, who is also president of Trinity Property Management, leases properties to some slightly more corporate chains. The Gap, for example, has occupied a Trinity Property building for over 35 years. It was one of the first national companies to come to the Square.

When searching for a new tenant, he says still tries to find something that creates a vibrant Square.

“We want to find something that adds to the mix and character of the Square,” DiGiovanni says.

TOURISM AND A GLOBAL BRAND

Tourists flood Mount Auburn Street on hot summer days, crowding the sidewalks and posing for pictures as chugging tour buses linger nearby. Some meander the streets, following bobbing umbrellas held tenuously aloft at the head of the pack.

Somewhere between eight and ten million tourists visit Harvard Square every year, Jillson estimates.

“They come from all over the world,” Jillson says. “When you’re walking through the streets you’re hearing languages from every corner of the globe.”

According to Robyn Culbertson, executive director of the Cambridge Office for Tourism, many are arriving from Asia. She says Asian and Chinese tourists have increased by 300 percent.

“Everyone is now rushing to figure out how to market to the Chinese,” Culbertson says. “Everyone is talking about translating their websites.”

Although tourists are drawn, Jillson says, to Harvard and its “global brand,” many patronize local businesses and leave captivated by the charm of Harvard Square.

Jillson says that the Harvard Square Business Associate has worked alongside Harvard to encourage tourism that actually boosts local business rather than simply shepherds tourists through.

“We’ve had lots of meetings between the HSBA and the university about how to accommodate the large number of buses, how to ensure that people can get off the bus and can actually wander through the square, visit the bookstores and meander through the streets,” Jillson said.

So far those efforts seem to be successful.

The influx has boosted business for the tour companies that have popped up to accommodate travelers. According to Jillson, they have witnessed a huge increase in demand.

Longstanding Harvard Square restaurants now rely on the constant stream of tourists.

Bartley, for example, has turned to the tourism industry to keep the Burger Cottage afloat. Bartley says that many longstanding Cambridge residents have left the Square as affordable housing has vanished. Tourists are the main customers he has left.

As landlords increased rents, Bartley says, tourists have helped the eatery survive.