Connecting the banks of River Danube and the Castle Hill, the Buda Castle Hill Funicular (Budavári Sikló) has been in service since 1870. Its construction was initiated by Ödön Széchenyi, son of the statesman Count István Széchenyi. Back then, this was the second of its kind in Europe. It was admitted to the list of UNESCO World Heritage sites in 1987 as a distinctive element of the Danube bank of Budapest. It runs on a 95-meter route of 50 meters elevation between Clark Ádám Square and the Sándor Palace. Although the Funicular is operated by the Budapest Transport Privately Held Corporation, the ordinary public-transport single tickets and passes are not valid for riding. The two cars (Margit and Gellért) are connected like counterbalancing pendulums: while one car runs uphill, the other goes downhill. It is a highly popular attraction, so be prepared for queues.