Schloss Thalstein, Heritage château in Jena, Germany.

Schloss Thalstein is a manor house on the slope of the Jenzig near Jena, between the Wenigenjena and Kunitz settlements. The property was called a Gut (estate) until 1868; the manor complex was extensively modernised between 1892 and 1902. A wrought-iron gate bears the inscription "FMA 1960".

The estate came under the control of the von Tümpling family starting in 1868, including a Prussian general who lived there until 1884. After 1960 the château changed hands and served various purposes for different groups.

The name Thalstein comes from the Talenstein rock recorded in Jena's 1406 tax book, where Albrecht Tümpling held land. Until 1868 documents called it a Gut, a farm estate, not a Schloss. The von Tümpling family kept its archive here and funded a family fideicommissum; a boundary stone dated 1891 still stands behind the Jenzighaus inn.

The building is a privately owned, decaying monument and is not open to visitors; it can only be viewed from outside. It stands between the Wenigenjena and Kunitz settlements, between the Jenzig hill and the Saale, a few hundred metres north of the Erlkönig statue. A boundary stone dated 1891 stands behind the Jenzighaus mountain inn.

The wrought-iron gate still bears the inscription "FMA 1960", recalling the VEB Fernmeldewerk Arnstadt, which took over the complex in 1960 and ran it as a holiday home. Since its sale by the Bundesvermögensamt in 2002 the listed building has decayed; in 2010 the owner, a Jena tax adviser, received the negative prize "Schwarzes Schaf der Denkmalpflege".