El Salvador's most famous criminal organization is MS-13, the sprawling network of drugs and violence that started with immigrants in Los Angeles and spread all over the Western hemisphere. If you're a member of MS-13 in El Salvador and you get arrested, hope to high heaven that you wind up in Penas Ciudad Barrios. Located in San Salvador, the population inside is entirely gang members, who run the prison like a city. A regiment of soldiers is positioned outside the prison walls to ensure that the maximum security inmates don't get any ideas, but inside it's a criminal free-for-all. There are no guards -- all rules and laws come from MS-13 leadership, not the government.