Royal Porcelain Manufactory (KPM), acquired by Frederick the Great in 1763. The Mausoleum , to the south-west of the Belvedere, was commissioned by Frederick William III to house the tomb of his lady consort [...] monument preservation. The Belvedere in the palace gardens formed part of the project commissioned by Frederick William II to redesign the park. The building, conceived by Karl Gotthard Langhans, was built in [...] The Mausoleum was first extended in 1841–1843 under Ludwig Ferdinand Hesse, after the death of Frederick William III himself, and then again around 1888–1894 to drawings by Albert Geyer, in order to i