It could be many things.
Check these websites to see if any of them make any sense in the context of your question.
http://www.google.com/search?hl=en&ie=ISO-8859-1&q=%22heart+of+the+nation%22
What the HECK is HEART OF THE NATION
2 answers
the capital of the country and i think it has to do with social studies youre welcome for your answer