'Mountain City' is a nickname commonly used to refer to cities that are located in mountainous regions. These cities are often characterized by their unique natural beauty, as well as their rich cultural heritage.

In China, for example, the city of Chongqing is often referred to as the 'Mountain City' due to its location in the Sichuan Basin surrounded by steep hills and mountains. This nickname reflects the city's rugged terrain and its history as a strategic military location during World War II.

Similarly, in the United States, cities such as Denver and Salt Lake City are also commonly referred to as 'Mountain Cities' due to their proximity to the Rocky Mountains. These cities are known for their outdoor recreational opportunities, as well as their thriving arts and culture scenes.

Overall, the nickname 'Mountain City' represents the unique character and natural beauty of cities located in mountainous regions around the world.