Leopoldstadt, the citys 2nd district, is separated from the city centre by the Danube Canal and by the River Danube to the north, forming an island with the neighbouring Brigittenau district. Named after the Habsburg Emperor Leopold I, it is largely residential following development along the canal in recent years, except for the huge Prater, a magnificent park. It was once the imperial hunting grounds, with its own amusement park, woodlands and sports facilities as well as an exhibition centre for trade fairs. From the early 17th century until the 1940s, Leopoldstadt was the home of Viennas thriving Jewish population including such luminaries as Sigmund Freud, Gustav Mahler and Theodor Herzl. Despite near annihilation during the Holocaust, the Jewish community survived and continues to live here in greatly reduced numbers. Once a workers bastion many of Leopoldstadt's older neighbourhoods have received a facelift and now attract a more exclusive upmarket set. The Hauptallee is pedestrianised and the U1 underground line now crosses Leopoldstadt linking it to the city centre (Innere Stadt) and Donaustadt to the east. A planned extension to the U2 underground line will also pass through Leopoldstadt.