You might complain about a lot of things in the city where you currently live. Pollution is really bad or the education system is a failure. You might also say that some people are rude or the cost of living is quite high. If you take a look at the 20 most dangerous cities in the world, you might feel grateful that you are somewhere else. These cities have seen all types of crimes and for some, the problems have escalated beyond what is tolerable. They are places you definitely want to avoid!