A memorial plate at St John's Church (the alleged place of the baptism) was unveiled a few years ago, commemorating the incident in the Czech and German languages. In 800 the city had 23,000 inhabitants, and by 1000 this had increased to 40,000. On 8 December 899 Arnulf of Carinthia, descendant of Charlemagne, died at Regensburg. In 1096, on the way to the First Crusade, Peter the Hermit led a mob of crusaders that attempted to force the mass conversion of the Jews of Regensburg and killed all those who resisted. Between 1135 and 1146, the Stone Bridge across the Danube was built at Regensburg. This bridge opened major international trade routes between northern Europe and Venice, and this began Regensburg's golden age as a residence of wealthy trading families. Regensburg became the cultural centre of southern Germany and was celebrated for its gold work and fabrics. In 1245 Regensburg became a Free Imperial City and was a trade centre before the shifting of trade routes in the late Middle Ages. In 1486, Regensburg became part of the Duchy of Bavaria, but its independence was restored by the Holy Roman Emperor ten years later. In the city took place the Diet of 1541, was adopted the Protestant Reformation in 1542 and its Town Council remained entirely Lutheran. From 1663 to 1806, the city was the permanent seat of the Imperial Diet of the Holy Roman Empire, which became known as the Perpetual Diet of Regensburg. Thus, Regensburg was one of the central towns of the Empire, attracting visitors in large numbers. A minority of the population remained Roman Catholic, and Roman Catholics were denied civic rights ('). Although the Imperial city had adopted the Reformation, the town remained the seat of a Roman Catholic bishop and several abbeys. Three of these, St. Emmeram, Niedermünster and Obermünster, were free imperial estates within the Holy Roman Empire, meaning that they were granted a seat and a vote at the Imperial Diet ('). So there was the unique situation that the town of Regensburg comprised five independent "states" (in terms of the Holy Roman Empire): the Protestant city itself, the Roman Catholic bishopric, and the three monasteries. In addition, it was seen as the traditional capital of the region Bavaria (not the state), acted as functional co-capital of the Empire (second to the Emperor's court at Vienna) due to the presence of the Perpetual Diet, and it was the residence of the Emperor's Commissary-Principal to the same diet, who with one very brief exception was a prince himself (for many years the Prince of Thurn and Taxis, still resident in the town).