The Pr?sidium stood on four pillars and for most of its height was square in cross-section. Not far above the dials, however, the corners of the square floor-plan were cleaved off, making it into an octagon, and not far above that, the octagon became a sixteen-sided polygon, and above that it became round. The roof of the Pr?sidium was a disk, or rather a lens, as it bulged up slightly in the middle to shed rainwater. It supported the megaliths, domes, penthouses, and turrets of the starhenge, which drove, and was driven by, the same clock-works that ran the dials.

Below each dial was a belfry, screened behind tracery. Below the belfries, the tower flung out plunging arcs of stone called buttresses to steady itself. Those found footing amid the topmost spires of four outlying towers, shorter and squatter than the Pr?sidium, but built to the same general plan. The towers were webbed to one another by systems of arches and spans of tracery that swallowed the lower half of the Pr?sidium and formed the broad plan of the Mynster.

The Mynster had a ceiling of stone, steeply vaulted. Above the vaults, a flat roof had been framed. Built upon that roof was the aerie of the Warden Fendant. Its inner court, squared around the Pr?sidium, was roofed and walled and diced up into store-rooms and headquarters, but its periphery was an open walkway on which the Fendant’s sentinels could pace a full circuit of the Mynster in a few minutes’ time, seeing to the horizon in all directions (except where blocked by a buttress, pier, spire, or pinnacle). This ledge was supported by dozens of close-spaced braces that curved up and out from the walls below. The end of each brace served as a perch for a gargoyle keeping eternal vigil.