20th Century America and the world in general. I think future generations will be amazed at how a fairly weak country at the start of the century became the most advanced country on Earth, complete with most of the major scientific discoveries of the 19th and 20th century, including the telephone, electric light (19th century), airplane, etc. and of course the atomic bomb and putting man into space (competing against the Russians)
I think in the long run, this is the civilization that will be studied and both admired and hated for it's innovations and horrible discoveries like the Bomb. Thanks to modern technology, we might be able to preserve historic events for the first time and future generations will be able to see, not just read about 9/11 (21st century), the San Francisco Earthquake of 1989, the explosion of the Challenger and even the assassination of JFK.
