Harbor

A dockyard where ships sail to distant realms to trade or make war.
Requirements-

Must be built in a town or capital.

Must be built adjecent to a large river or sea. (or lake connected to a large river)

1 storage facility where trade goods can be stored.

3 trading stalls of which at least one should represent the faction of which you want a trader.

1 sleeping location for the allied merchant.

2 ships.

Benefits-

Gets another realms trader inside your city for extra riches.