Council of Thieves - Adventure Path
The entries to the sewers of Westcrown are well secured to prevent thieves and rebels from using them as a base of operations. This has not prevented the resistance from using it as a hiding place and as a way of moving around without attracting too much attention.
Like the sewers found in many major cities, it is populated by a host of weak monsters, such as Torbles.
Westcrown’s sewer are an amazing feat of engineering. Their design is efficient and necessitate almost no maintenance. Most people, including city officials need to give no thoughts to these sewers.