San Francisco's waterfront is on the National Register of Historic Places for good reason. Its picturesque old landmarks, like the Ferry Building and the Bay Bridge, have been featured in many vintage books, TV shows and movies — from the stories and novels of Jack London to the 1970s TV series The Streets of San Francisco.

The future of San Francisco's waterfront, however, isn't secure.

In 2016, the National Trust for Historic Preservation put part of the city's urban shoreline on its list of the U.S.'s most endangered historic places, in part because of the threat of sea level rise. Now, San Francisco is considering drastic measures to save its historic shoreline.

The waterfront landmarks of many cities are under increasing threat from floods and rising sea levels brought on by human-driven climate change. St. Mark's Basilica in Venice, Italy and the Venice Beach boardwalk in Los Angeles face similar challenges to San Francisco.

But the growing magnitude and frequency of the climate-related threats, the high costs and effort involved in saving heritage sites, and competing ideas about what's worth saving and what isn't, can make it hard for cities to know where their priorities lie.

"The whole issue of climate change and historic preservation intersects right at the waterfront," said Elaine Forbes, executive director of the Port of San Francisco. The agency manages a 7.5-mile stretch of the city's Bay-facing waterfront.

As she watched the ferries come and go on a sunny afternoon near her office at one of the city's recently renovated historic piers, Forbes said sea level rise hasn't historically been as much of a threat to San Francisco as major earthquakes.

That's changed.

Parts of the main road that runs along the waterfront have flooded from heavy rains in recent years. The state estimates the water could rise roughly up to two and a half feet above its current level by 2060, and potentially up to seven feet by the turn of the century.

"I would say it's clear by mid-century we need to have had intervention," Forbes said.

The city is figuring out how to strengthen its sea wall, sections of which are 140 years old. It also plans to physically move some of the waterfront's historic structures out of harm's way.

The most prominent of these is the Ferry Building.

"To prepare for sea level rise, which is coming, we may need to lift this building up to seven feet," Forbes said, gazing up at the heavily-touristed landmark.

The Ferry Building sits in the middle of the waterfront. It's been a beacon to incoming ferry riders since the late 1890s. The high end boutiques and gourmet eateries inside attract droves of visitors. It's hard to imagine what it will take to physically raise the enormous white structure with its soaring clock-tower up that high.

"We've heard loud and clear everywhere: It's to be saved," Forbes said, adding that this will happen — no matter the cost or effort involved. The specifics of the project have yet to be released.

'What's gonna happen to the rest of the city?'

Since 2017, the city has conducted extensive studies and outreach to help determine how to make its shoreline more resilient. Last year, it sought feedback on a set of proposed strategies through public meetings, focus groups and shoreline walks. A recent report states "preserving the historic nature of the Embarcadero" — that's the part of the waterfront where the Ferry Building sits — as one of the public's priorities.

Not everyone NPR spoke with necessarily feels the same way.

"The Ferry Building, if you wanna raise it seven feet, that's gonna save the Ferry Building. But what's gonna happen to the rest of the city?" said Sanaz Tahernia, a digital healthcare professional who lives in one of San Francisco's shoreline neighborhoods. "The community is what makes San Francisco. Not these buildings."

Tahernia is one of several people NPR chatted with on the waterfront recently about what's top of mind when it comes to protecting San Francisco landmarks from sea level rise. They all had differing viewpoints.

"It would just be something to see the change, if it goes good or if it's bad," said Raymond Tillery, a student and skateboarder who grew up in one of the city's waterfront areas. "Like if it's for the people or if it's for profit or something."

"It would be a shame for all these old buildings to be destroyed," said Mary Mulcrone, a visitor from Ireland with family in the San Francisco Bay Area. "But I think all over the world with global warming, we're going to see whole countries underwater."

"I don't wanna see any part of the city affected if we can do anything about it, honestly," said Dakari Tillery, a security guard at the Ferry Building and San Francisco native.

Saving the city's shoreline

Preserving historic buildings is just a small piece of San Francisco's overall Waterfront Resilience Program. Other priorities include beefing up emergency response systems and protecting natural habitats.

The Port of San Francisco estimates the project could cost billions of dollars. Forbes said there are tough decisions to make around safeguarding the future of the city's waterfront cultural heritage.

In a statement to NPR, San Francisco's Port Authority said ongoing community feedback is helping to inform its draft plan for saving the city's shoreline. That plan is expected to be released early next year.

"Where heritage is often most vital is where it is lived and used," said Marcy Rockman, a Washington, D.C.-based consultant and researcher focused on the impact of human-caused climate change on cultural heritage.

Rockman said all neighborhoods have heritage, not just ones with plaques on the buildings. She said she hopes San Francisco's approach will balance care for less visible yet deeply valuable aspects of the city, with prominent heritage places like the Ferry Building.

"We cannot hold back the sea. But we can carry forward some of what's important about this place," Rockman said. "What would you like that to be?"