The event is free and starts at 9 a.m. and runs until 4 p.m.
CicLAvia closes streets to car traffic and opens them for people to walk, skate, bike, play, and explore parts of Los Angeles County.
The event is being held downtown because UCLA began there as a teacher's college.
Car traffic will be off-limits on streets in Westlake, Chinatown, Little Tokyo, Boyle Heights, and Downtown Los Angeles.
The final CicLAvia event is scheduled for Dec. 8 and will be in the San Fernando Valley.