The greater Austin area is home to myriad art galleries and museums, and on one day every year, dozens of those institutions open their doors, free of charge, to anybody who'd like to pop in and soak up a little culture. It happens on the third Sunday in September, also known as Austin Museum Day, which this year falls on this coming Sunday.

"This is our 20th year of hosting Austin Museum Day," says Austin Museum Partnership co-chair Lani Gonzalez. "That's a very exciting milestone."

The day has grown in scale over the past 20 years, with nearly 40 museums, art galleries, and cultural institutions taking part this year. "It's just exploded," says Nick Nobel, the other co-chair for Austin Museum Partnership. "People love to go out and explore, [and] there are all these different pockets of activity going on."

"And it's not just Austin," says Gonzalez. " We also have participating instutions in Johnson City, with the Science Mill, there's the Williamson Museum in Georgetown, and the Texas Wendish Heritage Museum in Giddings. So you can also get out of the city."

Gonzalez and Nobel are both hoping that people will visit multiple museums and make a day of it. "You know, if one person gets to go and visit a museum for free that they wouldn't maybe have thought to go to, or had the means to go to, I think that's what it's really all about," says Gonzalez.

Nobel's setting his sights a little higher. "My goal is -- how many people live in Austin now? It's a couple million, right? I would say at least two million would be a great achieveable goal."

Austin Museum Day is Sunday, Sept. 17. See a full listing of participating museums here.