Alright, so here is the exact location for The Open Canvas Project- LA Art Walk :

We will be in front of Spring Street Park, on Spring Street, between 4th and 6th, in the Arts District.

Here is a link to the exact address and a map!  And there is 5$ flat rate parking right across the street, in addition to many others.

http://la.curbed.com/archives/2013/07/historic_cores_spring_street_park_getting_dogchildren_divider.php