The city and its management are at the core of the Civilization. By expanding the city and maintaining its health and happiness, the ruler is more likely to increase his power. Each city houses the population of a Civilization. Cities employ <l:6,98>workers<e>, <l:6,99>slaves<e>, and specialists to build units, <l:6,65>improvements<e>, and <l:6,64>Wonders<e>. Settlers  can <l:6,48>build<e> cities on most land terrain tiles. Only <l:1,65>Marines<e>, <l:1,55>Space Marines<e> and <l:1,60>Swarm<e> can unload into a city guarded by enemy units. Cities are also targets of enemy special attacks. When attacked, cities can become wary, which is represented by an icon of an eye above the city. Wary cities lessen the success rate of a special attack by half for several turns.