Luke Air Force Base, Arizona

Luke AFB calls itself the largest fighter training base in the world, which it may be, though Nevada's Nellis Air Force Base is also big, as are some others. The base uses the 1.8 million-acre Barry M. Goldwater Range in southwestern Arizona for training. Luke itself is about 4,200 acres. Luke AFB has been designated as the primary training base for the new F-35 Lightning II fighter, which at a cost of $1 trillion, is one of the most expensive weapons ever produced.