1. In vanilla, every Great person had the ability to start a golden aeg (the turns decreased each time this was used). With Great Artists being able to Culture Bomb.
2. In G&K, The Golden Age ability was restricted to Great Artists and the culture bomb moved to Citadel construction (if you constructed a citadel via Great General it would expand your borders.
3. Monuements were a unique Culture improvement exlusive to Great Artists the exact same that academies are unique Science improvement exlusive to Great Scientists.