Lunar Crater is the most famous feature of the Lunar Crater Volcanic Field east of Tonopah, Nevada.  It is 3,600 feet wide w/ a depth of 430 feet.  Its age is not fully known, though the estimate puts it around 72,000-190,000 years old.  A tephra ring in the crater is dated to 600,000 ± 30,000 to 224,000 ± 43,000 years ago.  The crater has been the test site for prototype Mars rovers as well as astronauts training in the Moon landings.  Over 200 volcanic vents have been identified within the region w/ the last eruption occurring roughly 10,000-38,000 years ago.  It was quite windy the day of my visit, perhaps a common phenomenon of such an open area.