It starts on the same street as the Parisian Café, though Ariadne has forgotten the book shop and a few other minor things. Here, Cobb allows her to experience the way a dreamer can build and manipulate dreams in order for her to better design dream worlds for the heist on Fischer's mind.
Ariadne is immediately able to comprehend the mechanics of the dream world and begins altering the architecture of the dream excessively, an action that Cobb warns will draw the attention of his projections. She eventually decides to build a bridge she knows in the real world. This causes Cobb to warn Ariadne not create dreams based on memories, because when memories begin to mix with dreams, the dreamer begins to lose track of reality.
Eventually, despite Cobb's best efforts, his projections assault Ariadne before Mal stabs her and wakes her up.