Privacy activists plan a massive march on Washington, D.C., this weekend demanding that Congress rein in the National Security Agency. The Saturday event, dubbed the Rally Against Mass Surveillance, is being organized by a coalition called Stop Watching Us

More than 570,000 people have signed a petition in support of the group, and more than 100 public advocacy organizations and companies will be represented at the march and rally. The rally is also being supported through a public service announcement featuring film celebrities like John Cusack, Maggie Gyllenhaal and Oliver Stone.

Activists will lobby Congress on Friday, asking for changes to the federal government’s policies regarding data collection. Their demands include changes to Section 215 of the USA Patriot Act of 2001, the state secrets privilege, and the FISA Amendments Act in order to stop blanket surveillance and to increase government transparency.

Activists also will call for the creation of a special committee to investigate the extent of the NSA’s domestic spying and recommend reforms. Lastly, the group is demanding that public officials found responsible for any unconstitutional surveillance be held accountable for their actions.

The march will begin at Washington, D.C.'s Union Station and will proceed to Union Square, in front of the Capitol Reflecting Pool. Besides speeches against illegal government surveillance, the rally also will include live music performances.

Organizations that have expressed support for the group include the Electronic Frontier Foundation, Mozilla, the American Civil Liberties Union, FreedomWorks, and dozens more. Notable names attached to the event include Tim Berners-Lee, inventor of the World Wide Web, Daniel Ellsberg, whistleblower of the Pentagon Papers, and Alexis Ohanian, founder of social news website Reddit.

The rally is marketed as the largest single rally against surveillance ever held, and it comes as the National Security Agency builds a $1.5 billion data center in Bluffdale, Utah.