Sebastian keeps running into Mia (Emma Stone), an aspiring actress. When they finally start clicking after a number of mis-steps, their first date is to be at the Rialto in South Pasadena to see "Rebel Without a Cause." She's late and can't find him in the dark theatre so she steps out on stage to look into the house. The still, from the first "La La Land" trailer, was featured on an a page about the film from Elle. The trailer is on YouTube, as is trailer #2 and a four minute making-of featurette.
Sebastian and Mia watching the film at the Rialto. It's a Dale Robinette photo for Lionsgate. See our page on the Rialto Theatre for more about this historic venue. It's currently closed awaiting its next act.
Later in the film the duo go to the El Rey Theatre on Wilshire Blvd. where pianist Sebastian is playing with a group called The Messengers, fronted by Keith (John Legend). We don't see much of the building itself. Our El Rey Theatre page has more about the 1937 vintage theatre, now used as a music club.
Mia puts together a one woman show. The exterior of the theatre she rents for the production is the Variety, 5253 W. Adams Blvd. The interiors were shot elsewhere. On our South, South Central and Southeast Theatres page you'll find our listing for the Variety Theatre, now a music club.
Other locations seen include the freeway interchange between the 105 and the 110 for the opening number, the Smokehouse Restaurant in Burbank (where Sebastian plays Christmas music), the Lighthouse Cafe in Hermosa Beach, the Hermosa beach pier, Angel's Flight, the Watts Towers, Griffith Observatory, and the Blind Donkey in Long Beach (Seb's nightclub at the end).
The N.Y. Times had a fine story "L.A. Trancendental: How 'La La land' Chases the Sublime" that included several shots from the film. On L.A. Curbed see "LA's Starring Role in 'La La Land'" and "The Ultimate 'La La Land' Filming location Map."
David Ng's December 25, 2016 L.A. Times story "'La La Land' looks beautiful but..." talks about the difficulties of location shooting for this film (and others) with so many historic locations vanishing.
USA Today has "Your La La Land Cheat Sheet." Architectural Digest weighed in with "La La Land Set Design" profiling designers David Wasco and Sandy Reynolds-Wasco. E Online has "The Official La la Land Guide To Los Angeles."
On IMDb: "La La Land"