Polar Hills can support cities, though not as well as in the flatter lands. In addition, movement is slowed, and <l:8,19>roads<e> are difficult to build. To their advantage, polar hills do afford a defensive bonus, and allow building of <l:8,3>mines<e>, or, at the later stages of civilisation, <l:8,2>Hydroponic Farms<e>. <l:6,25>Rivers<e> greatly enhance this terrain.