Goblin Lawn

The Goblin Lawn is a large grassy plain between Porto Vallum and Silver Creek (click the mini-map to enlarge it):

At lower character levels it is a great place to get experience because of the sheer number of enemies. At later levels however most people use the Goblin Lawn just to "farm" runes. For some unknown reason the Goblins tend to drop runes a LOT, especially the "boss" level Goblin Shamans. Although you can find other enemy types in this area it will mostly be Goblins: