What is the building behind the 18th green at st Andrews?

The building behind the 18th green at St Andrews is the iconic Royal and Ancient Golf Club of St Andrews (R&A) clubhouse. Established in 1754, it serves as a central hub for the game of golf and is renowned for its historical significance and impressive architecture. The clubhouse is also closely associated with the Rules of Golf and has been pivotal in shaping the sport's traditions.