Udaipur is called the 'Lake City' (or City of Lakes) because it has an interconnected system of artificial lakes - Lake Pichola, Fateh Sagar, Udai Sagar, and Swaroop Sagar. These lakes were built by the Maharanas of Mewar for water supply and recreation. Jaisalmer, Jodhpur, and Hyderabad are not known for their lake systems.