United States of America
Formerly a British colony, now United States (hereinafter "USA") are considered the most powerful country in the world. Being the fourth in the world in area and the third in number of citizens with over 300 million citizens living on area bigger than India or Brazil. There are 49 states that are in the North America with the 50th laying in the Pacific ocean. That gives us 50 states plus Washington D.C., which is not a state but separate district. It is that way because Washington is the capital of the USA.
USA is a federal republic. And even there is one central government, there is a great deal of decentralization. That was proved by recent permission to smoke marijuana in only two states and yet it being prohibited by the federal law.
There is also power divided into three parts. Executive, legislative and judicial. Legislative power is in hands of the Congress, executive in hands of the President and judicial is in hands of Supreme court.
There are lot of "must see" places in the USA because they are so large. If I should exclude NYC as a separate question I must mention Las Vegas as a paradise for gamblers, Los Angeles as a birth place of most of the great movies (Hollywood) and many others like Chicago, San Francisco or San Diego. I could just spit on you the names of the cities and I think that you can say that you know almost all of them.
There are Rocky mountains on the west and Appalachian mountains on the east. Those are two greatest mountain ranges in USA. Then there should be mentioned Yellowstone park, Death Valley, Grand Canyon. From the rivers Colorado river, Rio Grande (forming part of the US-Mexican border), Mississippi river or Houston river. I could just mention Niagara falls and you should think of Great Lakes. There are so many things that I can't possibly include them all.
Like I could talk about Czech Republic on and on I can talk about USA as well. About economics and politics problems, about cultural clashes between Hispanics and nowadays habitants. For all I know I could sing you the anthem of the marines :D (or at least the first part)