Each of us can pave the way to find necessary information in web with several cliques. Such a process is called data-based routing. Did you know that it was solution of the Königsberg bridge problem that urged the member of Saint-Petersburg Academy of Sciences Leonhard Paul Euler to create fundamental theory of such a routing? It was renamed Kaliningrad after the Second World War. The Königsberg fortress founded by the Teutonic Knights in the year 1255 on the key point mount in the mouth of the Pregel River fallen into the Baltic Sea has spread out very quickly. Three separate settlements Altstadt, Kneiphof and Löbenicht arose around it. As early as the 14th century each town had its laws and a town hall, an army, a river harbour, a fire station. And each town was enclosed with a separate fortress wall. Towns were cooperating, but sometimes were quarrelling with each other. In the 18th century the King Friedrich Wilhelm ordered to unite these three towns under the crown of Königsberg and built bridges over the Pregel River. There were seven. They were called Merchant’s Bridge, Green Bridge, Blacksmith’s bridge, Connecting Bridge, Wooden Bridge, High Bridge, and Honey Bridge. The Pregel River was navigable, therefore there were drawbridges. The problem was to find a walk through the city that would cross each bridge once and only once. No one knows who was the first to think about it. Many people tried to find solution during walking. And it was Leonhard Euler who managed to work out a rule and proved that the problem has no solution. This is only one of the numerous histories and legends of the ancient Prussian town. Königsberg forts and Königsberg klopses, colony of Amolinau villas, the famous zoo and Amber Museum - don't miss a program with Eugenia Altfeld about Kaliningrad on RTG TV channel.