The city of Kaliningrad, located on the Baltic coastline in a portion of Russian territory between Poland and Lithuania, was once known as Königsberg, when it formed part of the territory of Old Prussia. The centre of the city was located on an island in the River Pregel.
The topography of Königsberg in 1652 is depicted on a map of Königsberg in 1652, by Merian-Erben. Seven Bridges cross the rivers in the centre of the city.
Source: http://commons.wikimedia.org/wiki/File:Image-Koenigsberg,_Map_by_Merian-Erben_1652.jpg
Lecture notes for undergraduate courses
Dr. David R. Wilkins