Why it matters
Opened in 2008 on cliffs east of St Andrews, the Castle Course is the only Links Trust course not on the coastal flats — it plays on bluffs 100 feet above the North Sea and gives you a 360° view back to the cathedral spire and the Old Course. The course is firm and modern, divisive (its severe greens come up on /r/golf in both rave and pan threads), but is unambiguously the best-views round in St Andrews.
How to play it
Walking encouraged; cart paths exist for those who need one. Ten minutes by car or taxi from the town clubhouse. Best paired as the last round of a St Andrews stay — finish on the cliffs after three days down on the links flats. Reddit consensus says don't make it your only Castle round; play it once, judge it for yourself, then return to the Old / New / Jubilee mix.