Now in its 18th year, Hardly Strictly Bluegrass drew thousands of San Franciscans to Golden Gate Park this weekend to hear more than 80 acts playing across six stages. It's the biggest annual music festival in Northern California, as well as one of the biggest in the world, with over 750,000 attendees — and it's also completely free.

The festival was started by San Francisco venture capitalist/philanthropist Warren Hellman, who began hosting the free event in 2001 and kept it going annually until he died in December 2011. It's now operated and funded by the Hellman Foundation.

Returning annual favorites included Alison Krauss, Emmylou Harris, Los Lobos, Mavis Staples, and Steve Earle; other acts included Lindsay Buckingham, Ani DiFranco, Ween, Booker T. Jones, Jeff Tweedy, Deer Tick, The Greyboy All-Stars with Karl Denson, and former Crosby, Stills & Nash guitarist Graham Nash. 

Here are some scenes from our weekend at the festival.