The Castle can be visited
New Castle Tettnang

The New Palace Tettnang in Baden-Württemberg is one of the architectural highlights of Upper Swabia. It shows its interiors, offering insights into the lifestyle of the Montfort noble family.
History+
Count Anton III von Montfort initiated the construction of this three-story, four-winged complex, as the Old Palace no longer met Baroque standards. The new building began on the site of a castle erected in the 12th century and destroyed in 1633, whose rubble had been cleared beforehand. Master builder Christoph Gessinger was commissioned with the construction, featuring pilasters that structure the facade and diagonal corner towers with staircases flanking the building sections. Artists such as Johann Michael Rottmayr and Dominikus Zimmermann designed the interior. However, the costs forced Count Anton III to halt work in 1728 and resign from government. His son Ernst completed the court chapel in 1731.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Tettnang_Neues_Schloss_Fassade_S%C3%BCdost.jpg
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 47.6700, 9.5850