The active player pays goods (from their warehouse and/or their Countinghouse cards) to build buildings or activate Carts and the Spokewheel. The necessary goods can be found on the tableaus.
Building buildings and activating Upgrade markers bring certain advantages to the player:
Buildings can only be built in the current location of a player ́s oxcart. In addition, Countinghouses, Ships and Mills can only be built in the cities in which the respective building site is shown and is not occupied by another building (in game rounds with only 2 or 3 players not all building sites are valid, some are marked with “3+” or “4” – this means they are only valid for buildings in game rounds with 3 or 4 players respectively).
Upgraded Cart and Spokewheel markers are turned face-up once they have been paid for.
Important: Countinghouses, Ship, Mill and Spokewheel can be built or activated in any order. However, the Cart upgrade has to be completed first with the small Cart and then the large Cart afterwards.