Any large city can have a complex setting, altough it is not compulsory (just think of the Randstat, Shanghai or New Orleans). Madrid has a certain terrain complexity, defined by the Manzanares (a quite tamed river), and the Abroñigal and Castellana creeks; Abroñigal is nowadays a corridor for the eastern M30 beltway and Castellana is the main north-south spine. The historical city began on the steep slopes of the eastern shore of the Manzanares, to later grow towards the east.