Build a fantasy mage tower citadel ...

Build a fantasy mage tower citadel on a circular waterfall island. The structure sits on a large circular elevated stone plateau (roughly 120–150 blocks diameter) rising about 30 blocks above a surrounding moat lake. The entire rim of the plateau is a continuous ring of waterfalls cascading down mossy grey cliff faces into the water below, with scattered rocky pillar outcrops standing in the lake around the base. On top of the plateau is a concentric octagonal fortress: two nested octagonal walls made of dark grey/silver stone with white stone trim. The outer wall ring has small pointed watchtower spires with black conical roofs at each corner (8 towers). Between the outer and inner walls is a green courtyard ring with trees, gardens, and small pathways. The inner octagonal wall is talle