Final answer:
The allegorical symbols in Pilgrim's Progress include The Celestial City and the Slough of Despond, each representing Heaven and despair respectively.
Step-by-step explanation:
The allegorical symbols found in Pilgrim's Progress include elements that represent complex ideas and concepts within the narrative. Most notably, The Celestial City symbolizes Heaven, or the ultimate spiritual destination, and the Slough of Despond represents the depths of despair and the difficulties one might face when burdened by sin and doubt. Pilgrim's Progress is rich with allegory, using these symbols to convey spiritual lessons and the struggles encountered on the protagonist's journey to enlightenment and salvation. Other allegorical elements in the story, like valleys, dungeons, and monsters, also contribute to the deeper meaning of the Christian's journey in faith.