Links courses remain most common in Ireland and Great Britain, especially in Scotland. The Open Championship is always played on links courses, and this is one of the main features which differentiates it from the three major championships held in the United States. The first exception to this was the 2004 PGA Championship, which was played on a links-style course, Whistling Straits, located near Sheboygan, Wisconsin. The 2015 U.S. Open was played at Chambers Bay, a British links-style course in University Place, Washington. Royal Adelaide Golf Club is a links course in Adelaide, South Australia, and was partly designed by Alister MacKenzie where he stated, "One finds a most delightful combination of sand dunes and fir trees. I have never seen a seaside course possess such magnificent sand craters, as those at Royal Adelaide."