Watch Tower Level 1
Prior to patch 1.05, it was unlike most mini dungeons in that the Watch Tower Level 1 was a fairly simple zone, which only had three different variations.
Following patch 1.05, it is now more complicated. It now shares a tile set with the Cathedral and is similar in size to Cathedral Level 1.
Watch Tower Level 2
The Watch Tower Level 2 is important because it's where you find Vendel the Armorsmith who gives you The Scavenged Scabbard event, which is the only way to get Scabbard of Talic the Defender, a journal entry needed for the achievement A Quick Study.