previous centuries and lies on the River Neckar. , the German weekly magazine Focus published a national survey according to which Tübingen had the highest quality of life of all cities in Germany. Factors taken into consideration included the infrastructure, the integration of bicycle lanes into the road system, a bus system connecting surrounding hills and valleys, late-night services, areas of the city that can be reached on foot, the pedestrianised old town, and other amenities and cultural events offered by the university. Tübingen is the city with the youngest average population in Germany. Main sights In central Tübingen, the Neckar divides briefly into two streams, forming the elongated Neckarinsel (Neckar Island), famous for its Platanenallee with high plane trees, which are around 200 years old. Pedestrians can reach the island via stairs on the narrow ends leading down from a bridge spanning the Neckar. During the summer, the Neckarinsel is occasionally the venue for concerts, plays, and literary readings. The row of historical houses across one side of the elongated Neckarinsel is called the Neckarfront and includes the house with adjoining tower where poet Friedrich Hölderlin stayed for the last 36 years of his life, as he struggled with mental instability. Tübingen's Altstadt (old town) survived the World War II due to the city's lack of heavy industry. The result is a growing domestic tourism business as visitors come to wander through one of the few completely intact historic Altstädte in Germany. The highlights of Tübingen include its crooked cobblestone lanes, narrow-stair alleyways picking their way through the hilly terrain, streets lined with canals, and well-maintained traditional half-timbered houses. Old city landmarks include the city hall on Markt Square and the Hohentübingen Castle, now part of the University of Tübingen. The central landmark is the Stiftskirche (Collegiate Church). Along with the rest of the city, the Stiftskirche was one of the first to convert to Martin Luther's protestant church. As such, it maintains (and carefully defends) several "Roman Catholic" features, such as patron saints. Below the Rathaus is a quiet, residential street called the Judengasse, the former Jewish neighborhood of Tübingen until the city's Jews were expelled in 1477. On the street corner is a plaque commemorating the fate of Tübingen's Jews. The centre of Tübingen is the site of weekly and seasonal events, including regular market days on the Holzmarkt by the Stiftskirche and the Marktplatz by the