Yes, there really is a downtown Los Angeles. They weren't just making it up for the old Perry Mason show. It might not be the same kind of tourist draw as Disneyworld or Universal Studios (with its fake downtown), but it does have stores and store fronts and places to walk and explore. There is even a subway down there, under the parking garage.
According to the Los Angeles Times, the new economy is having an interesting
impact on the downtown area. Building occupancy is rising and so are rental
prices, but the new offices are not packed with people, they are packed
with network routers, web servers and stuff like that. While Los Angeles
may have exploded the idea of downtown as a place to work, it still makes
a nice communications switching and processing node. Centralization is not
dead, at least not until all these machines can start telecommuting like
everyone else.