Why did Moscow become a mega city?

There are a number of reasons why Moscow became a mega city.

* Historical factors: Moscow has been the capital of Russia for over 800 years, and as such has always been a centre of power and influence. This has led to the city attracting people from all over the country, both for work and for leisure.

* Geographic factors: Moscow is located at the crossroads of Europe and Asia, and has played an important role in trade and commerce for centuries. This has also contributed to the city's growth.

* Economic factors: Moscow is the economic centre of Russia, and home to many of the country's largest companies. This has created a lot of jobs, and attracted people from all over the country to the city in search of work.

* Cultural factors: Moscow is a major cultural centre, and home to some of the world's most famous museums, theatres, and opera houses. This has made the city a popular destination for tourists, both domestic and foreign.

* Administrative factors: As the capital city, Moscow is home to the Russian government and many other important administrative bodies. This has also contributed to the city's size and importance.

As a result of all of these factors, Moscow has grown into a mega city with a population of over 12 million people.