The Location of Calle de los Negros is now a park that can be seen to the SE from the gazebo in the Plaza at Olivera Street. It was the roughest, most dangerous street in US history. A few hundred feet of brothels, gambling hells and saloons. It saw dozens if not a few hundred killings over the course of its years. The Chinese Massacre was an international event that eventually led to the obliteration of the "wickedest street in the west" altogether.
I'm glad the history guy covered this. According to FBI statistics and Bossecker's studies, Los Angeles in the 1850s had a higher homicide rate than any other place at any time in American history. To steal his tag-line, events like the existence of Calle de los Negros, the Nicaraguan Filibuster War, or the Baja/Sonora Filibustering expeditions are lost chapters of American history that deserve to be remembered.
-Dave