Specs Twelve Adler, North Beach.

The hardest dive bar to find in San Francisco.

Specs Twelve Adler Museum Cafe, known to the regulars simply as Specs, sits on a one-block alley off Columbus Avenue in North Beach. The alley is named for the playwright William Saroyan. The bar's address is 12. The door is unmarked except for a small green awning. The first three times you walk past it, you will not see it. That is by design.

Specs opened in 1968, founded by a former merchant marine called Richard Specs Simmons. Specs himself sat on the corner stool until he died in 2012. The bar then passed to a long-time bartender. The room has not changed in any way the regulars would notice.

Why this matters. Specs is a dive bar in the deep San Francisco tradition: founded by a working sailor, decorated by his shipmates, and committed to serving them at honest prices. The maritime memorabilia is real. The whaler harpoon over the bar was donated by a customer in 1971. The signed photograph of a 1953 Norwegian crew is the crew of a ship that sank in 1956.

The donated maritime archive.

Every surface in Specs is covered with seafaring artefacts donated by customers across forty-plus years. Crew patches from twenty-eight nationalities are pinned to the back wall. A whale baleen hangs above the door. A signed photograph of the captain of the QE2 sits in a frame next to a tin of unopened sailor's pipe tobacco from 1962. Three full whaling harpoons are mounted across the ceiling beam. A sextant from a Liberty Ship is bolted to the wall above the gentleman's toilet door.

The bartender will tell you any story you ask about. The unwritten rule is that you only ask about one item per visit. The stories take a long time. They are worth waiting for. A slow Tuesday night with two regulars at the bar, listening to the bartender tell the story of how the Liberty Ship sextant got there, is the Specs experience that the guidebooks cannot reproduce.

Anchor Steam and the Specs Special.

The drink list at Specs is short and unwritten. The regulars order one of three things and the bartenders pour them fast.

• Anchor Steam: the San Francisco beer, on tap, six dollars. The bartender will pull it for you without asking after your second visit.
• The Specs Special: dark rum, lime, sugar, dash of bitters. Eight dollars. Specs invented this on his ship in 1959. The recipe is taped to the inside of the cooler door.
• Boilermaker: Anchor Steam plus a shot of well bourbon, eight dollars total. The classic San Francisco dock worker pour.
• The wine option: a bottle of California red sits behind the bar at thirty dollars. It has been on the shelf for at least the last six months. We recommend the boilermaker instead.
• The food option: there is none. The bar serves pretzels.

9pm Tuesday. The local hour.

Specs opens at 5pm and closes at 2am every night. The peak hour is 11pm Friday and Saturday, when the City Lights bookstore crowd from across the alley filters in for a third drink. The local hour is 9pm Tuesday: the room is half full, the bar has eight stools open, and you can hear the conversation at the next stool.

Sunday is a quieter day. The bartenders open at 5pm and the first hour is reserved for a small group of regulars who walk over from City Lights with paperbacks. Read your book. Order Anchor Steam. Listen to the conversation at the bar. This is the most undersold experience in San Francisco's hospitality.

Avoid Friday before 8pm. The early hour gets a small spillover crowd from the financial district that has not yet acquired the patience the bar requires.

The unmarked door is the door.

From Columbus Avenue, walk past the City Lights bookstore. Cross Broadway. Turn right onto William Saroyan Place, a one-block alley that most San Franciscans walk past without noticing. The alley is short, fifty metres long. Specs is on the left, halfway down. The green awning has the number 12 in gold. There is no signage.

The interior is dimmer than the alley. Give your eyes thirty seconds to adjust. The bar is a long L on the right wall. Stools at the bar, two booths in the back, eight tables in the middle. Take a stool at the bar your first visit. The bartender will look at you and pour Anchor Steam.

Cards are accepted. There is no minimum. Tip in cash if you can: the bartenders prefer it.

Forty dollars per person, three hours.

Plan for thirty-five to forty-five dollars per person for a three-hour visit. That covers four drinks, a tip per round, and the small extra you should leave the bartender at the end if they tell you the harpoon story. A pair drinks for seventy-five dollars. A four-top for one hundred and fifty.

The bar does not run tabs for first-time customers without a card. After your second visit, the bartender will let you run a tab on cash. After your fifth visit, the bartender will know your name. After your tenth, you will get the seat near the back booth that has the best sight line on the maritime corner.

The North Beach reading crowd.

Specs draws from three concentric circles. The innermost is a small group of merchant mariners and former dock workers, retired now, who drink slowly at the bar five days a week. The middle is the City Lights bookstore crowd: poets, used-book dealers, the occasional Beat-era survivor. The outer is the North Beach evening crowd, who arrive after a long dinner at Tony's or Tosca and want a quiet third drink.

You will not find a tech crowd at Specs. The bar has refused to install Wi-Fi. That refusal is the editorial position of the room. Phones are tolerated but not encouraged. The bartender will not, under any circumstances, charge your phone behind the bar.

Specs is a quiet bar with rules.

• Do not photograph the maritime artefacts. The bartenders will ask you to put your phone away.
• Do not bring a group larger than four. The bar holds maybe forty souls and your six-top will dominate the room.
• Do not order a craft cocktail. The Specs Special is the cocktail. Everything else is a beer or a shot.
• Do not arrive after midnight on a Saturday. The line is around the alley.
• Do not engage the bartender about the harpoon if they are pulling beers fast. Wait for the slow moment. Ask once. Listen.
• Do not, ever, ask for the Wi-Fi password. The bar will say no, and you will feel small.
• Do not bring food in from outside. Specs does not serve food and does not want yours either. The bartenders will ask you to take it back to the alley.

Tony's pizza, Specs, City Lights, Vesuvio.

The classic North Beach evening: dinner at Tony's Pizza Napoletana on Stockton, two slices of Margherita, a glass of Sangiovese. Walk to Specs at 9pm for the Anchor Steam and the harpoon story. Cross the alley to City Lights bookstore at 11pm and browse the upstairs poetry room until 11:30pm. End at Vesuvio Cafe across Jack Kerouac Alley for one more, watching the rest of North Beach go home.

For more North Beach bars, see our San Francisco city guide, the hidden gems list, and the companion Vesuvio entry on this list.

Yes. The most quietly perfect dive bar in California.