Bochum is a city in the state of North Rhine-Westphalia, Germany and part of the Arnsberg region. It is located in the Ruhr area and is surrounded by the cities (in clockwise direction) of Herne, Castrop-Rauxel, Dortmund, Witten, Hattingen, Essen and Gelsenkirchen. With a population of nearly 365,000, it is the 16th most populous city in Germany.GeographyGeographical positionThe city lies on the low rolling hills of Bochum land ridge , part of the Ruhrhöhen between the Ruhr and Emscher rivers at the border of the southern and northern Ruhr coal region. The highest point of the city is at Kemnader Straße in Stiepel at 196 metres above sea level; the lowest point is 43 metres at the Blumenkamp in Hordel.The terrain of Bochum is characterised by rolling hills that rarely have more than three per cent graduation. Steeper graduation can be found at the Harpener Hellweg near the Berghofer Holz nature reserve , at Westenfelder Straße in the borough of Wattenscheid , or at Kemnader Straße, which begins at the banks of the Ruhr in Stiepel , and rises to its highest point in the centre of Stiepel .