Where: Erfstadt-Liblar, Germany
Constructed: 1851-1854
Accessible: no, but the park
surrounding the castle is.
Important fact:
Schloss Gracht was originally an outbuilding of Haus Buschfeld. It served as a military hospital in the 18th century and then became ruinous.
The new castle then replaced the ruin.
These days, it is used as a private hospital.