The Southern California Coastal Water Research Project recently began mapping LA's lost Ballona Creek watershed, which once spanned thousands of acres and ranged from freshwater ponds to marshes to meadows for several centuries.
European colonists later came and formed the city's first street grid, destroying around a third of these wetlands.
Archival photos from the USC Libraries show what LA looked like before it became a modern municipality. Take a look at the city's transformation.