At first glance of this aerial shot of First National / Warner Bros. Studios, I wondered what mines are in LA? And why would Warners paint a huge sign on top of one of their soundstages pointing to one? But when I saw that this shot was taken in 1928, I realized that the sign was saying to pilots: Mines Airfield is 14 miles that-a-way. 1928 was the year that Warners bought First National and that the LA city council Mines Field as the site of Los Angeles International Airport, which opened in 1930.