Gravel Pit

The Gravel Pit is a sovereign structure, enabled by scaffolding, which accelerates stone production.

Each level of gravel pit on any city's sovereign squares increases the stone gathering rate by about 1% (0.2% per stone plot). To build or upgrade a gravel pit on a tile, the owning city must have a sovereignty claim of matching level on the tile, and have achieved all the research prerequisites.

Economics

Building and upkeep costs

Level	Build Cost
	Wood Natural resource	Clay Natural resource	Iron Natural resource	Stone Natural resource	Measured span of time either expressed as components ([Ad] [Bh] [Cm] [Ds]) or one to three ordinals ([[hhh:]mm:]ss). Times are always exact to the second.
1	20	20	30	10	3:00
2	196	196	294	98	26:00
3	2,624	2,624	3,936	1,312	3:34:00
4	25,820	25,820	38,730	12,910	18:10:00
5	183,176	183,176	274,768	91,592	2d 13h 20m 61:20:00

Sovereign structures for natural resources have no upkeep.