Final answer:
Barcelona is the city situated at the mouths of the Llobregat and Besos Rivers, known for its cultural significance and as a major metropolitan area.
Step-by-step explanation:
The city that lies on the mouths of the Llobregat and Besos River is Barcelona. Barcelona is a major city located in the northeast of the Iberian Peninsula, facing the Mediterranean Sea, and is known for its rich culture, architecture, and history.
The Llobregat and Besos rivers serve as the natural borders of the city's metropolitan area to the southwest and the northeast, respectively.