Orc Cave

The Orc Cave can be found East of Khorad-Nur, there are two entrances to this cave at the Xs:

The inside of the cave looks like this:

There are a variety of Orcs and Tarantulas throughout the cave and having two entrances is great for re-spawning the cave.  The Orcs can give pretty good experience and drops, especially the "champion" and "boss" level Orcish Champions. This is a favorite leveling location, particularly for characters around levels 20-40: