In the 1995 film Batman Forever, Bruce Wayne remarks to Dick Grayson that it would be tough going if he left Wayne Manor as the circus he had performed with would be "half way to Metropolis". To this Dick replies that all he wants to do is avenge his parents death by killing Two-Face.
Metropolis is mentioned often in Batman: Arkham City. These mentions show that Batman and Talia al Ghul had a date in Metropolis and Hugo Strange was planning to build another prison in Metropolis similar to Arkham City. Also, the password for a lock you can break with the cytographic sequencer in Arkham City is Metropolis. That lock is near the museum on the subway and it is on one of the cars and opens a door to a car which has a Riddler Trophy to collect inside.
Within the DC Universe, Metropolis is the home of Superman, it is portrayed as one of the largest and wealthiest cities on Earth. Since then, Metropolis has become a city inspired by New York City, Chicago, Cleveland, Detroit, Toronto, Vancouver, and Los Angeles. Most of the notable landmarks in Metropolis are based on real-life landmarks in New York City.