City

Cities are large humanoid settlements that develop organically from towns whose access to abundant water and food sources are matched by geographical access to resources, practical trade routes, navigable waters and stable political environments. The largest cities will possess rare conditions, such as the sole access to large natural harbours, it's location as a trading gateway and their development as centers of spiritual or intellectual thinking.

Constantinople, one of the largest cities in the world, has an excellent harbour, powerful defensive capabilities, stands astride two of the world's most important trade routes and for more than a thousand years, acted as one of the world's great religious centers. Today, it is the political center of the vast Ottoman Empire. Due to its inherent characteristics, it's dominance as a city was inevitable.

In one degree or another, all cities, even the smallest, possess similar characteristics — they occur and thrive in those locations in the world suited to an expansion of population, political purpose and commerce. As a rule of thumb, a city is a settlement with 5,000 or more inhabitants.