Every year in January, Los Angeles hosts a Free Museum Day for the majority of the city’s museums. This means for one day only, admission is free along with/or parking. (Check the museum you are interested in for parking info-not all of them have free parking!)
For 2016, it’s the last Saturday of January–the 30th. (For the Jewish-American museums, Saturday is the sabbatical instead of Sunday. All their museums will be open on Sunday, January 31 instead of the 30th.)
To see a list of participating museums and their addresses: List of LA Museums for January 30, 2016.
Official website is here: http://www.socalmuseums.org/free-for-all/
*If you are a Metro rider, check out the website (https://www.metro.net/service/discounts/) for discounts on museum day. There will be many offers and rewards for taking the Metro! Just make sure to show your TAP, LA Employee ID, or Metro Employee ID at the destinations to get your discount/reward.