Few people know that the Los Feliz/Silverlake area of Los Angeles (adjacent to Griffith Park) once had a drive-in theatre -- apparently a twin. It opened in March, 1950 and closed in October, 1956. The Golden State Freeway was built on top of it. Since I posted this, readers have helped me find out some more information about it, including directing me to this article that appeared in 2012 in the Los Feliz Ledger:
Below, Andrew Ralston sent me this picture of Silver Lake and Atwater Village in 1953 from the Los Angeles Public Library archives. The Los Feliz Drive-in is visible left of center next to the Hyperion Bridge. It appears there may have been signage on the backside of the screen tower next to the bridge.
A commenter below referred me to an excellent site, Historic Aerials.com. Above, the site of the Los Feliz Drive-in in 1948. The Hyperion Bridge is just south, crossing the Los Angeles River. There appears to be some sort of industrial building at the site at this time.
Plainly visible here is the Los Feliz Drive-in from this aerial shot in 1955. Notice the curved terraces for cars, clearly showing that the drive-in was indeed a twin. The concession stand/projection booth is in the middle.
The 5 Freeway was built soon after, as seen in this 1972 aerial shot. As you can see, the freeway occupies about half of the land where the drive-in once stood.