Some golf courses are out of this world. A keen golfer has a choice of over 36,000 courses around the world, with about half of those in the United States alone. While opinion on what constitutes the "best" courses, author Chris McLeod highlights some of the world's great courses based on four key criteria: the challenge, the scenery, the accommodating and the tradition. Of course the quality of the course itself also comes into play. From the Holy Grail courses, such as Augusta and the Old Course at St Andrews, to some lesser known courses worthy of being added to your bucket list, McLeod has compiled here an inspiring list for golf enthusiasts.