Castle Town Sewers
The Castle Town Sewers are a location in Twilight Princess. They are situated beneath the grounds of Hyrule Castle and Castle Town. The sewers appear to be largely abandoned and are infested with vicious monsters. This location is visited by Link on two separate occasions. It's first ventured through when Link is dragged into the Twilight and locked away within the dungeons of Hyrule Castle. It is further explored later on in the game after Zant gravely injures Midna and Link is tasked with taking her to Princess Zelda.
Story
Upon awakening in the prisons that lie beneath Hyrule Castle, Wolf Link attempts to move, but he is bound to a shackle on his left paw. After attempting to break the shackle, a mysterious figure appears before him. This is in fact Midna, a cursed Imp. Link first sees Midna as a threat, but she soon offers her assistance. Now at ease, Wolf Link stops growling and lets her help him escape his imprisonment. Midna proceeds to break the chain with her Twilight Magic. After finding a small dig spot, Link escapes the cell and teams up with Midna. The pair navigate their way through the puzzling sewers and find themselves on Hyrule Castle's rooftops, where they later encounter Princess Zelda.
Link must revisit this location later in the plot, when on his quest to retrieve the Master Sword. The young hero, now cursed in Wolf Form, searches desperately for the entrance to Hyrule Castle, in an attempt to find Princess Zelda, at Midna's request. Through the help of Telma's Cat, Louise, Link is able to find a secret entrance that leads to the sewers. The young hero now finds himself in a new area and he must utilize the sticks within the vicinity in order to burn the spider webs and delve deeper through the dungeons. Link soon comes upon the spiraling staircase, which he encountered on his previous visit. After crossing the broken sections of the staircase, Link finds himself at the top, where he can once again traverse the rooftops of Hyrule Castle.