The Prater has been a recreational area since the early 15th century, initially as hunting grounds for the Habsburgs but later as a place of enjoyment for all of Vienna’s citizens when Emperor Josef II opened them to the public in 1766. The Prater gradually developed to include merry-go-rounds and other rides, cafés and eateries. In 1873, the Prater was the site of the World’s Fair. The Giant Ferris Wheel (Riesenrad) was erected in 1897 to celebrate the 50th anniversary of the reign of Empereror Franz Joseph I. The wheel itself spans 200 feet (about 60 m.). 15 cabins and the upholding structure weigh a total of 430.5 t and rotate at the speed of 0.65 m/sec.