pg 44. Borderers must choose from Plains, Swamp, Hills, Forests or Mountains. Zamorians get +1 to Climb, Hide, Listen, Move Silently and Spot in underground or urban conditions, so that would be helpful.
Thieves can choose a free feat at 6th level if they pick that option off thier list (last option) and could pick Fleet-footed to increase thier speed to compensate for any deductin when moving through ruins (which presumable counts as difficult ground, so each single square counts as if it were two - pg12).
The only types of terrain are desert/sandy, forest, hills, jungle, moor, mountains, plains, swamp or tundra/frozen. Geographical terrain. Urban is varried and would either fall under clear or difficult (or even full move=5ft move for exceptionally difficult terrain). However, difficult or worse terrain features can exist in any tertrain type, so it's best to assume that Urban terrain (where ruins might otherwise get categorized) is clear.
Also, Ruins could be present in any of the above terrain types (coverd by desert sands, overgrown by jungle, frozen over with ice, etc.) so where they are clear, those terrain feature penalties would apply. Otherwise they'd count as difficult or difficult +.