Long, long ago (and a short distance away) no building was allowed to rise higher than LA's City Hall:

For decades, developers lobbied the city to relax the restriction, to no avail. Los Angeles made only one exception: in 1926, it allowed its own City Hall to soar to 454 feet. It would remain the city's tallest building for 40 years.

Lots more about the history of the downtown LA skyline in that post by Nathan Masters, from KCET's wonderful blog, SoCal Focus.