its resources are maintained as the city grows, but the player is free to manage the city directly. This feature can be utilized to turn a part of the population into one of several specialized occupations; at the cost of having one less space from the city, these specialists increase gathering and production of the resources of their targeted specializations. Each city can only produce one military unit or one building at a time; any additional units or buildings are placed into a queue. The rate of construction is determined by the amount of material collected from the surrounding spaces; players can also choose to speed production by sacrificing gold or population if they adopt the required governmental policy; called civics. The player can instead specialize the city towards gathering a particular resource instead of constructing additional units or buildings. Also, in order to produce some units or buildings, certain resources must be collected within the empire and connected to the empires trade network by roads or harbours (for example, horses are needed for mounted units, and iron for swords, while stone or marble increase production of certain Wonders.). Buildings perform any number of different functions depending on building type; for example, early buildings such as granaries improve food storage to boost the city's growth and barracks produce better military units, while later buildings such as factories increase general production levels. There are also a number of unique buildings throughout the game. Most notable are World Wonders, which can be accessed through research nodes in the technology tree and construction through the worker unit. World Wonders provide advantages that are unique to each civilization, as they are limited to only one or two players. Through buildings and specialists, each city also generates the "Culture" resource that contributes towards both the area upon which the city can influence for extracting resources and the overall civilization's cultural value. When two cities of different civilizations are adjacent to each other, the culture values of each city influences the space they can control; it is even possible that a city close to another civilization's city will join that civilization if their culture is strong enough. The high levels of culture gathering and attainment are also one of the default conditions that can be used to win the game. Technology, government and religion Once the first city has been founded, the player can select their