Presidential candidate and Massachusetts Sen. Elizabeth Warren made waves in March when she called to break up the monopoly of big tech companies — and on Wednesday, she brought the message straight to the source.

A billboard that simply reads “Break Up Big Tech” sits on Fourth and Townsend streets, near the Caltrain stop that many tech workers of the metaphorical and physical Silicon Valley frequent. It’s a bold statement to not only place the billboard in San Francisco, but in an area where tech companies are clustered. Employees headed westward to Pinterest, Airbnb, or Zynga near Seventh Street are more likely to see the billboard but Lyft, Dropbox, and Cloudfare are a couple blocks from the station as well.

Warren’s focus, however, is on the tech giants of Facebook, Google, and Amazon that she says were able to amass wealth and power through weak antitrust enforcement. Microsoft was once targeted for violating anti-monopoly laws, she reminded her potential primary voters in a Medium post.

“Today’s big tech companies have too much power — too much power over our economy, our society, and our democracy,” Warren wrote. “They’ve bulldozed competition, used our private information for profit, and tilted the playing field against everyone else. And in the process, they have hurt small businesses and stifled innovation.”

Warren proposed legislation that would stop platforms earning $25 billion or more from owning any participants on the platform. That means Amazon would have to ditch its Amazon Marketplace, which sells directly to online shoppers on the site, and Google’s ad exchange couldn’t be part of the company that runs Google’s search engine.

The Massachusetts senator also promised to appoint regulators who would undo takeovers, like Amazon to Whole Foods, Facebook to What’s App and Instagram, and Google to Waze to give smaller companies a chance again.

Given the revolt from tech workers refusing to work for companies who have problematic contracts with the government (see: Palantir’s agreement with Immigration and Customs Enforcement) and Facebook co-founder Chris Hughes’ call to break up the social media giant, Warren may have an audience in the tech world.

But as San Francisco constantly reminds national outlets, there’s more to the city than tech workers — its residents are constantly fighting against the negative impacts of powerful tech companies at their doorstep. With this week’s billboard, we have a hunch Warren is aware of this.