* '''179 A.D.''' The Romans built the Fortress "Castra Regina" at the most northernmost end of the Danube river.* '''739''' A bishopric is established in Regensburg. Several older cathedrals are destroyed before construction of the present one begins in 1273, taking nearly 600 years to complete.* '''1146''' The ''Steinerne Bruecke'' (Stone Bridge) is completed. Trade connections to Paris, Venice and even Novgorod have made Regensburg a prosperous city. * '''1245''' Having been one of the largest German cities during the Middle Ages, Regensburg becomes a free imperial city.*'''1663–1806:''' Regensburg is the seat of the Perpetual Imperial Diet (Reichstag) of the Holy Roman Empire of the German Nation.*'''1806:''' Holy Roman Empire dissolved in Regensburg during the Napoleonic Wars.*'''1995:''' 750th anniversary of free imperial city status. http://wikitravel.org/en/Regensburg