These days, we’re so conditioned to flock to the new and trendy.

But there’s a lot to be said for the classic that’s withstood the test of time.

Sam’s Grill in San Francisco is a true testament to that. It was established in 1867. Let that sink in for a moment. The restaurant opened three years before Golden Gate Park was created, 11 years before the San Francisco Public Library opened, and 31 years before the Ferry Building was built.

It oozes history. And it’s a slice of old-school San Francisco you don’t find much of these days except at other venerated restaurants such as Swan’s Oyster Depot and the House of Prime Rib.

Five years ago, Sam’s Grill almost shuttered. But Peter Quartaroli, one of its former servers and maitre d’s who went on to become a screenwriter, decided to buy the place with help from some loyal customers.

“My Dad used to work in restaurants. And I have worked at downtown San Francisco restaurants since I was a kid,” Quartaroli says. “So many places that became part of the fabric of the city are disappearing. I didn’t want to see Sam’s go away. It was so important to keep it.”

So Quartaroli set about preserving its history while also making it relevant in this era.

Stepping inside Sam’s Grill is a little like stepping back into the Golden Age of San Francisco. Muliti-generations of families have made this a second home. Former San Francisco Mayor Willie Brown still dines here at least twice a week. I couldn’t even remember the last time I visited Sam’s Grill, when I was invited in a couple weeks ago as a guest of Quartaroli.

The main dining room by the bar is wide open and has a clubby feel. But for a real experience that can’t be found at many places these days, sit in a booth. Yes, it’s one of those three-sided, wood booths cordoned off with its own curtain to pull close. If you choose to go all clandestine, your server won’t disturb you until you pull the curtain open again. Or you can always use the buzzer on the wall — that still works — to summon your server.

Quartaroli brought in veteran Chef David Gingrass, who helped open such iconic San Francisco restaurants as Postrio and Hawthorne Lane. Gingrass was brought on as a consulting chef, but ended up enjoying it so much that he’s now on-board full-time.

Gingrass has refined some of the classics, and added a section of daily specials.

A place like this demands a classic cocktail, which is just what I indulged in. The Sam’s Negroni ($13) is a stiff blend of Tanqueray, vermouth and Campari, with herbaceous character and a woodsy orange edge.

Bread is served upon request, and it is — naturally — Boudin sourdough, along with a ramekin of butter covered with an “S” paper lid. When’s the last time you saw that?

Or the last time you had Celery Victor ($10)? Here, the poached, chilled celery is given a bolder flair with a garlic chili vinaigrette and white anchovies. If you think celery is boring, this will change your mind.

Shrimp scampi ($12) brings forth a plate of plump shrimp in a slightly spicy lemon herb butter. You know how some scampi tastes like it’s been drowned in butter? That’s not the case here. There’s a nice butteriness to the dish, but not so much that it takes over everything.

The seafood salad ($21) was split so that my husband and I could share it. The cold, crisp romaine hearts were dressed in a lively vinaigrette with capers. Bay shrimp and sweet Dungeness crab meat were strewn over the top. It’s a nice, lighter option than the Louis salad on the menu.

The Lazy Man’s Cioppino ($35) is a bountiful bowl brimming with Dungeness crab meat, clams, mussels, calamari, and shrimp in a tomato broth that’s got a little hit of spice and plenty of intense seafood broth flavor. Nothing was overcooked in it — no easy feat when dealing with so many different types of seafood. You don’t need a bib to eat this version, in which the crab meat is already extricated for you. You just need plenty of the garlic bread that comes alongside to dunk happily into the broth.

Grilled whole branzino ($30) is one of the newer additions to the menu. The fish arrives with crisp skin, fluffy flaky flesh, and a nice smokiness that brings out its natural sweetness. A fresh mix of summer tomatoes and cucumbers adds a Mediterranean touch. House-made Calabrian chili oil comes in a little cup off to the side so you can smear as much as you like on the fish.

Because the two long rows of booths have only a narrow path between them, don’t expect your Bananas Foster ($7) to come rolling to you on a cart, where it’s flambeed in front of you. There’s just no room for that.

Instead, the dessert will be brought to the table with no fanfare. But it doesn’t need any. With warm bananas in a heady cinnamon, brown sugar bourbon sauce over vanilla gelato, your spoon will slip into it easily, and again and again.

Quartaroli knows a place as venerable as Sam’s can be a little intimidating to newcomers. That’s why he added the patio three years ago. Built in the alley, it’s a comfortable spot with patio lounge chairs, a small bar, and strings of romantic lights. There’s even a real wood floor (so you’re not dining on the actual asphalt) that folds up onto itself at the end of the night.

Last December, he also opened Sam’s Tavern next door in what was an old stamp store. With plenty of big screens, it’s a great place to catch a televised game. The bar also has an extra feature that should not be missed: the exposed brick wall behind it dates back to 1906. In fact, when Quartaroli uncovered it after taking over the space, it still smelled like smoke from the fires that broke out following the 1906 earthquake. How amazing is that?

Newcomers might flock to the patio or to Sam’s Tavern initially. Baby steps, baby steps. But Quartaroli hopes afterward that they venture into Sam’s Grill for the ultimate experience — a sense of a cherished past that fortunately still lives on.