Unfortunately, I cannot locate a picture of the huge mausoleum. Rotenberg belo it is a village which is a part of the Untertürkheim district of the City of Stuttgart, Germany. The area overlooks Untertürkheim and other villages.
Württemberg Mausoleum
By 1819 the castle was in ruins. King William I of Württemberg (whose father, Frederick III, Duke of Württemberg became king in 1806) built Württemberg Mausoleum on the hill for his second wife Queen Catherine (1788–1819) (daughter of Tsar Paul I of Russia and Sophie Dorothea of Württemberg ). After his death in 1864, King William was also buried in the mausoleum (German: "Grabkapelle Württemberg"). Today the mausoleum is an important local landmark as it is visible from many areas of east Stuttgart.
Note: Rotenberg should not be confused with other towns with similar sounding names which are better known. 40 km SW is Rottenburg am Neckar, 80 km N is Rothenberg and 90 km NE Rothenburg ob der Tauber.(see wikepedia)