At the center of Stuttgart lies a series of gardens which are popular with families and cyclists. Because of its shape on a map, the locals refer to it as the "Green U". The Green U starts with the old Schlossgarten, castle gardens first mentioned in records in 1350. The modern park stretches down to the river Neckar and is divided into the upper garden (bordering the Old Castle, the Main Station, the State Theater and the State Parliament building), and the middle and lower gardens – a total of 61 hectares. The park also houses Stuttgart planetarium.