Moscow is the capital and most populous city of Russia, with 13.2 million residents within the city limits and 17 million within the urban area. Moscow is the northernmost and coldest megacity and metropolis on Earth. It is home to the Ostankino Tower, the tallest free standing structure in Europe; the Federation Tower, the second-tallest skyscraper in Europe; and the Moscow International Business Center. The city is well known for its architecture, particularly its historic buildings such as Saint Basil’s Cathedral with its colourful architectural style. With over 40 percent of its territory covered by greenery, it is one of the greenest capitals and major cities in Europe and the world, having the largest forest in an urban area within its borders—more than any other major city. Moscow wheelchair access is average, despite the city being the seat of power of the Government of Russia. The Kremlin, a medieval city-fortress that is today the residence for work of the President of Russia. The Moscow Kremlin and Red Square are also one of several World Heritage Sites in the city.