After an unscientific survey of most every corner of San Francisco I have come to a very unsurprising conclusion — North Beach is still the heart of San Francisco.

The city has moved south in the past few years, south of South of Market, even south of the ballpark. Mission Bay is full of new buildings, new energy and new ideas. It’s amazing down there, but I recalled what Herb Caen said about heaven: “It ain’t bad, but it ain’t San Francisco.”

Neither is Chinatown, the Castro, or the Mission. They have their special flavors, but they are only a portion of what we think of when we think of San Francisco. I’m fond of Noe Valley, West Portal, the Marina and all the western neighborhoods, each a small town in the larger city, part of the fabric.

Which brings us back to North Beach. I went back again the other day. The skies had just cleared, and the new grass in Washington Square was as green as springtime.

The square, which of course is not square at all, is the neighborhood’s living room. It is surrounded by the city, its past and present. In one corner is a monument to Juana Briones, who raised cattle and vegetables in the days when the town was still called Yerba Buena.

The park is in a little valley: Russian Hill on one side, Telegraph Hill on the other. It is an urban space, a city park personified. Yet if you look down Columbus Avenue you can see the gray green peak of Mount Tamalpais, where wild animals still roam.

The square is rimmed by businesses with deep roots: Original Joe’s, Victoria Pastry, the Italian Athletic Club, Mario’s Bohemian Cigar Store Cafe, the Liguria bakery. On Christmas week, the line under the faded gilt sign of the bakery goes around the corner and up Filbert Street — expatriate San Franciscans, back in the old neighborhood to buy a holiday treat of the original focaccia bread from the Soracco family. It reminds them of the city they left but can’t forget.

That’s one of the things Doris Watkins likes about North Beach. The neighborhood, she says, is still true “to those who loved it yesterday and those who love it today.”

She skipped her morning Luk Tung Kuen exercise class to talk about North Beach. Her class and others like it — graceful stretching exercises led by an elderly Chinese lady — are a daily fixture in Washington Square. Luk Tung Kuen, which has 36 different exercises, is similar but distinct from other Eastern exercise programs. They all exist, some with music, some not, side by side on the grass every day, slow dances to good health and long life.

Visitors always notice the Asian groups in front of SS Peter and Paul Church, the Italian cathedral of the west, its face inscribed with words from Dante’s “Paradiso.”

Lawrence Ferlinghetti wrote about the old Italian men who sat in Washington Square on sunny afternoons, smoking black Toscanello cigars and listening to the church bells, the “slow, slow tolling,” for the last rites; funerals on weekday mornings, weddings on Saturday afternoons.

The old Italian men who sat on the park benches are mostly gone now, replaced by old Chinese men. The Italian flavor of the neighborhood changed over the years, now it’s more Asian. But a strong Italian presence remains, and the green white red tricolor still flies above the Italian Athletic Club every day on Washington Square.

There was a celebration there three weeks ago, when the square reopened after a $3 million overhaul that lasted seven months. The new square came out looking very much like the old one.

“It’s the same, but it’s better,” Watkins said.

Watkins and her husband, Wes, have lived in “the hood,” as she calls it, for 25 years.

“This is our silver anniversary Christmas,” she said. They came from the Central Coast for new jobs and stayed. They like the character of the place, the neighborhood feel. People care about each other, she said.

It is surely not suburbia: Doris and Wes are not homeowners. Instead they have a rent-controlled home, up 52 steps from the street. They own a car but have no garage; the hunt for a parking spot is always the ultimate North Beach game.

I prowled around a bit more: a salami and cheese sandwich on a hard roll at the Molinari delicatessen, a rainy afternoon drink at Gino and Carlo, a stroll along Upper Grant Avenue to look at the boutique shops.

Upper Grant was once the main street of Beat San Francisco. Now it’s full of high-end shops. It is also a residential street: Little Bubbles, a coin laundry, is next to Little Vine, a wine shop and cheesemonger.

“This street is unique,” said Jim Schein, who with wife Marti owns an antique map store. It’s not the new San Francisco for sure. “North Beach is old school,” he said.

Carl Nolte’s column appears Sundays. Email: cnolte@sfchronicle.com Twitter: @carlnoltesf