Colonising
To found or colonise is the easiest way of obtaining a second city.
Settlement Sites
Whilst exploring the World Map you may have already noticed some grey banners. These banners mark places where you are able to establish a new city.
Requirements
Buildings
Units
To found a city you require a Colony Ship. This can be build in the Harbour once it has been researched, and will cost 
10,000 
10,000 
10,000.
Culture
You must also have sufficient Culture Points to found a new city. For your second city this will always be three points.
The Process of Colonising
Once you have meet all the requirements, it is easy to begin founding your new city.
- First find a suitable place you wish to colonise. It is preferable to find a location relatively close to your first city so your Colony Ship doesn't have to travel too far.
- Begin by clicking on your selected siteand going to the "Found a new city" tab.
- Select the units you wish to sail to the city. In addition to the Colony Ship you will need to send some other units to help defend against potential attackers. Remember you will need to send all land units in Transport Ships or Fast Transport Ships.
- Once you are done press the Establish City button and your fleet will set sail.
Depending on the distance between your cities it may take a while for your fleet to arrive. Once they do arrive you will receive a report, and the troops aboard your Colony Ship will automatically begin constructing the first building in your new city. Constructing the first building in a new city will take 24 hours, and the resources for the building are included in the cost of the Colony Ship.
When this building is completed you will be alerted in the City Overview.
Congratulations - you now have a second city!