Both the Hall of Prayer for Good Harvests and the Circular Mound Altar are round, each standing on a square yard, again representing Heaven and Earth.

The collection of medieval buildings dominated by the 13th-century Palazzo dei Priori, now the town hall, loomed over the square, making it seem small and dark.

The new, larger building would be more energy efficient, costing less per square foot to heat and cool than the old hall.