6: The Old White Course at The Greenbrier — White Sulphur Springs, West Virginia
This 7,300-yard-long course has been conquered by some golfers including Kevin Chappell and Stuart Appleby who have achieved shot sub-60 rounds however it is extremely unlikely that many others will be able to do the same. With a USGA rating of 76, it is evidently one of the more challenging courses out there as it features uneven greens and compact fairways added to its marathon length.