Penza (Пе́нза, ˈpjɛnzə) is the largest city and administrative center of Penza Oblast, Russia. It is located on the Sura River, southeast of Moscow. As of the 2010 Census, Penza had a population of 517,311, making it the 36th-largest city in Russia. The city name is a hydronym and means in Penza (/'penjzɑ/) from pen 'end of (genitive)' and sa(ra) 'swampy river'. This central quarter occupies the territory on which the wooden fortress Penza was once located, therefore it is sometimes called the Serf. The architectural concept of the old fortress, erected on the eastern slope of the mountain above the river, predetermined the direction of the first streets. The direction and location of the first streets were set by the passage towers of the fortress and the orientation of its walls. This is how the first six streets of the city were formed. Subsequently, the names were fixed to them: Governor's, Lekarskaya, Moscow, Nikolskaya, Sadovaya and Teatralnaya. An important element of the urban development of the city is that the square of the fortress created a network of streets converging at right angles. Initially, there was no proper harmony in them. Often the difficult terrain of the area forced the direction and width of the road to change. Here and there, spontaneous development took shape. Nevertheless, the urban planning matrix was created and predetermined the development of the city for several centuries. During the reign of Empress Catherine the Great, the first general plan of Penza was drawn up, it was approved on October 6, 1785. The city was rebuilt anew in accordance with the rectilinear structure of St. Petersburg. The plan of the city, in its central part practically did not change, as it fully complied with the new norms of Russian urban planning. The mutually perpendicular orientation of the streets and the accompanying division of the urban environment into standard quarters was the original and distinctive feature of Penza.