In the city of Regensburg, in the state of Bavaria, in southeast Germany

 Why are things as they are and not otherwise?

--Johannes Kepler, a German astronomer, mathematician, astrologer, natural philosopher, and writer.
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(in the city of Regensburg in Bavaria Land state) In southeast Germany. It lies on the right bank of the Danube River along its most northerly course, where it is joined by the Regen River, about 65 miles (105 km) northeast of Munich. Bavaria is a region in southern Germany known for its rich history, culture, and traditions. Founded by the Romans in 179 AD as Casta Regina (meaning Fortress by the River Regen), Regensburg is one of Germany's oldest towns today. Many flock to see the wonderfully intact Old City and its many medieval structures. The 12th-century Stone Bridge was used by Crusaders en route to the Holy Land. The Regensburg Cathedral (or Dom St. Peter) is one of southern Germany's finest examples of Gothic architecture. The capital of the Oberpfalz region of Bavaria, Regensburg, dates back to Roman times and was the first capital of Bavaria. (Though big on the historical wow factor, today’s Regensburg is a laid-back and unpretentious sort of place, and its tangle of old streets is a joy to wander. The Roman north gate (Porta Praetoria) and parts of the walls survive. The capital of the dukes of Bavaria from 530, Regensburg, was made a bishopric in 739 and shortly afterward became the capital of the Carolingians. The only free imperial city in the duchy of Bavaria from 1245, Regensburg was exceedingly prosperous in the 12th and 13th centuries. It was taken by the Swedes and later by imperial troops in the Thirty Years’ War (17th century) and was destroyed by the French in 1809. (It passed to Bavaria in 1810.)

+ Despite repeated bombings in WWII, Regensburg sustained little damage, and most of the city’s medieval buildings survived. Its imposing patricians’ houses (12th–14th century) are unique in Germany, and the Steinerne Brücke (Stone Bridge; 1135–46) across the Danube is a medieval constructional marvel that was repaired after the war. The cathedral of St. Peter (1275–1524) is one of the most important Gothic churches in Bavaria, with 14th-century stained-glass windows and two Romanesque chapels in the adjoining cloisters; its Boys’ Choir (Regensburger Domspatzen) is well known. the 13th-century Dominican Church and the Minorite Church (ca. 1250–1350). The buildings of St. Emmeram’s Abbey (founded 7th century) have been the palace of the princes of Thurn and Taxis since 1812, and there are remains of the 13th-century Herzogshof, the residence of the Bavarian dukes.

+ Regensburg also features museums of shipping and natural history. The astronomer Johannes Kepler died here (in 1630)

+ The only free imperial city in the duchy of Bavaria from 1245, Regensburg was exceedingly prosperous in the 12th and 13th centuries. It was taken by the Swedes and later by imperial troops in the Thirty Years’ War (17th century) and was destroyed by the French in 1809. (It passed to Bavaria in 1810.)