The Mausoleum of Prince Ernst in Stadthagen, Lower Saxony, is a mausoleum erected by Ernst of Schaumburg and his widow Hedwig of Hesse-Kassel in the years 1620–1627. Its unusual architecture and the resurrection monument by Adrian de Vries make it a site of European rank. The crypt was used as burial place of the House of Schaumburg and the House of Schaumburg-Lippe until 1915.
The mausoleum, attached to the chancel of Stadthagen parish church St. Martini, is a domed heptagon in Italian renaissance style designed by Giovanni Maria Nosseni. Four of its walls are furnished with Latin inscribed epitaphs for Prince Ernst, his parents, and his wife, framed by aediculas with Italian marble columns.
Wikipedia https://en.wikipedia.org/wiki/Mausoleum_of_Prince_Ernst
Address 5 Am Kirchhof, Stadthagen 31655, Germany
Coordinates 52°19'24.345" N 9°12'26.309" E