Public Works and Tile Improvements

Improvements

• Improvements are placed on tiles inside your borders (a few may be built outside). Each costs Public Works and takes a number of turns to complete; its page has both.
• A tile only yields anything when one of the city's citizens works it, so an improvement is only worth what the citizen on it produces.
• Roads coexist with other improvements; anything else is one per tile. Replacing an improvement pays the Clear Improvement fee on top.
• Building on a forest clears it first, for free, over a few turns; the improvement goes up after. The forest stays until the clear finishes, and only then hands the nearest city 15.
• Trade goods need their own improvement before a city can use them. See Trade Goods.

Roads and bridges

• A road connects a good's tile to the city that uses it, and connects cities to each other.
• A city with a road to your capital earns +2 and +2 every turn.
• Stepping onto a tile with a finished road costs 0.375 movement points, wherever the step comes from and whatever the terrain under the road (a mountain pass still pays a share of the mountain), and stepping off a road onto any tile costs no more than that either (except into a mountain pass). A bridge costs the same as a road. Inside the borders of a civ you are at war with, roads give your units nothing. A land unit can also walk across one of your own transports with room for it, for the same cost, as long as it reaches the far side that turn. Road movement improves by +10% with Civil Engineering, +10% with Mapmaking and +30% with Railroad.
• Caravans travel roads cheaply too, and religion spreads faster between cities joined by road.
• Bridges carry a road across a river.

Pillage and repair

• An enemy unit standing on one of your improvements can pillage it, leaving rubble. The rubble sits there for 30 turns.
• Roads can be pillaged too. The first pillage takes a tile's improvement and the next one takes its road. A pillaged road is simply gone, with no rubble, and has to be laid again. Any road on enemy land can be pillaged, whoever built it. Bridges cannot be pillaged. Barbarian raiders burn roads as readily as farms.
• Rebuilding the same improvement on its rubble is a repair at 75% of the usual cost. Building anything else there clears the rubble first.
• A pillaged fort or wall defends nothing until it is repaired.

Terraforming

Terraforming reshapes the tile itself: clearing forest or swamp, levelling hills, planting trees. It is paid for from the same pool, costs more and takes longer, and the change is permanent. See Terraforming.

All improvements

• Bridge: 10, 3 turns.
• Farm: 12, 2 turns; +2.
• Fish Boats: 12, 1 turn; +2.
• Hunting Lodge: 9, 3 turns; +1 +1.
• Mine: 12, 3 turns; +2.
• Pasture: 18, 2 turns; +1 +2.
• Plantation: 12, 2 turns; +1 +2.
• Road: 5, 3 turns.
• Watch Tower: 24, 5 turns.