This site in Turkey is, if experts are right about its purpose, the oldest temple built by human hands. It's more than eleven thousand years old, and yet we didn't know it was there until Klaus Schmidt noticed it in 2008.
The stonework at the site is masterful, and has taught us much about how skilled our ancestors were at the art of construction. It appears they had a better aptitude for it than we do; they made the whole temple without any metal tools.