Dan Callahan,
# 13 at Pinehurst # 2 might be considered a fortress green.
Tommy Naccarato,
I wouldn't consider # 2 at Riviera as a fortress green.
Tom Doak,
My definition would be a massive, steeply and highly elevated green with serious drop offs.
The putting surface at # 8 at NGLA is not visible from the fairway.
One of the brilliant illusions created on that green is when the hole is cut along the far right side of the green. From the fairway, the pin looks like it's suspended on a gangplank 15 feet off the green.
Many who play the hole with the pin in those locations play safe, far left, leaving themselves with devilish recoveries or putts. Those who attack the pin usually regret doing so, since the margins of error are so slight.
Jeff Brauer,
I can see your point on a public golf course, but I don't think the same holds true for a private golf course.