Serapeum of Saqqara

Hundred-ton granite boxes, polished flat to the micron, sealed in the dark. For bulls, officially.

The Serapeum of Saqqara holds ~24 granite sarcophagi of 70-100 tons, polished to fine tolerance inside narrow rock-cut galleries. Officially burial boxes for Apis bulls — though the finest boxes were found empty and the logistics of placing them underground remain impressive by any standard. It connects the precision-granite problem to Giza (same material, same open method question).