It was needle-shaped and had sliding walls, plaz windows, adjustable floors and flowmetal surface. Since it could change at Omnius' will it all seemed alive.
It stood in the main plaza in the center of the city and on top the Omnius Prime was manifested.
After Corrin-Omnius was defeated by ThurrOm and SeurOm, the two everminds stripped away the pretentious decorations and attempts at artwork. The Spire was simply downshaped and tucked into a giant protected vault beneath the main plaza.