Put Time in Prospective

As I was watching the History 2 channel, I found it entirely impossible to comprehend the amount of time to build an empire like the Ottoman (1299-1923). I've always had a difficult time grasping time and distances in history lessons especially growing up in the United States of America where many states are as big, if not larger, than many European countries. It's like trying to appreciate how much the US debt is. It just tough to apprehend something that occurred so long ago without the technological advances that we are so accustomed to having. Some of the things built are just marvelous and took much more time, effort, and probably patience (which the world may not enough of). Here are some things to put things in prospective:
Great Pyramid of Gaza- 20 years to build (2560-2540BC)
Great Wall of China (Built in about 275 years during different periods of time)
Taj Mahal- 30 years to build (1623-1653)
410 days to build the Empire State Building (1929-1931)
14 years to carve Mount Rushmore (1927-1941)
2 years for the Willis Tower (Sears Tower) (1970-1973)
7 years for One World Trade Center (Freedom Tower)- (2006-Opening today)
14 years for Duke Nukem to be released (1997-2011)
Most dinosaurs became extinction at the end of the Mesozoic Era (66 millions years ago)
Pangaea formed about 300 million years ago and began to break apart 200 millions years ago.
The Earth is about 4.54 billion years old.