The wall protects all buildings inside the city, preventing the destruction of workshops during a siege.
New walls can be built by the town's Lord Mayor to increase the amount of available space for constructing housing and businesses. Housing and city buildings can only be built inside the wall, so the Town Walls should be enlarged as soon as possible.
Enlarging Town Walls
Walls can be expanded if the Town Council allows it (players can propose such an offer in the Town Hall if their rank is high enough). There can be two expansions, Level 2 and Level 3.
You don't have to wait for the second wall to be built in order to build the third one, you just need to place all the wall pieces and build a business or two outside the second wall, and you'll have the option to make an offer for the Level 3 enlargement.
Bricks: 10 Timber: 1 Iron Goods: 1
Bricks: 25 Timber: 2 Iron Goods: 2
Each wall consists of multiple segments and three gates.
The number of wall segments varies from town to town, a Level 2 wall consists of around 90-100 pieces, a Level 3 wall consists of around 160-170 pieces.
When all segments of the new wall have been placed, the old wall disappears. It was believed that a town could not be besieged until the entire wall is finished, but it appears to be untrue.
Wall construction will slow down if other buildings are ordered simultaneously (a portion of the builders will be assigned to other tasks).
AI wall construction
Key parts of this section are based on information from the german tips collection.
Computer-controlled Lord Mayors build walls very slowly, so it is convenient to know how they operate.
It turns out that they only place wall segments on specific dates, so it makes sense to sell enough Bricks and Iron Goods to the markets right before these construction sprees.