What's the biggest irony in the world ? The largest city in sierra leone is called freetown .
Why do you see irony in the name of the city?
I don't know what you are saying.
If I remember correctly what I learned in my geography class, Freetown and the nation of Liberia were both named because they were meant to be a refuge for slaves who were able to return to the continent of Africa.  There is nothing ironic about this choice of name, even if history did not work out that way.